Cooked whole, as is:
Commonly, the egg is cooked whole and as such can be a featured item at breakfast, lunch, dinner, or as a midmorning, midafternoon, or midnight repast. The following are notes on the various applications of heat usefully deployed on whole eggs:
Poached: Poaching in water that’s just barely at a simmer is arguably the best way to cook an egg whole. The temperature is gentle and so keeps the egg tender. (Do we ever pause to consider how lucky it is that it’s the white and not the yolk that sets first? Easy to take for granted, but it would be a different culinary universe if they set at the same time.) The cooking medium doesn’t impart its own flavor, nor does the heat brown the protein and thus introduce new flavors, so the flavor of a poached egg is unadulterated, elegant egg.
An egg white has two different consistencies; part of it is loose, watery, and part is dense, viscous. Crack an egg on a plate and you can see the different textures. When you gently ease an egg into hot water, the loose white congeals into useless shreds, while the dense part of the white congeals appealingly around the yolk. Many cookbooks recommend that the water be acidulated to help prevent the flyaway white from forming; I’ve never been able to see the difference between eggs cooked in vinegar-spiked water and plain water, and the acidic water needs to be rinsed off after cooking, so adding acid to your poaching water is not recommended. Fresh eggs tend to have a greater proportion of the dense white than factory eggs, and this does make a big difference in the size and appearance of your finished poach.
Harold McGee, in noting the egg white disparity, offers this excellent recommendation for making prettier poached eggs (and when done properly, they’re very beautiful to look at, which is part of the fun of cooking and serving them). Crack the egg into a ramekin. Pour the egg from the ramekin into a large perforated spoon and briefly allow the loose white to drain off, then return the egg to the ramekin to proceed with the poaching. This greatly reduces the amount of flyaway white.
Poached eggs should be cooked just until the white is set, and no longer, removed with a slotted spoon, allowed to shed the excess water, and served immediately. Alternatively, they may be moved from the pot to an ice bath until thoroughly chilled and can be easily reheated as needed within a day or so (an excellent strategy when serving numerous people).
Fried: Fried eggs are delicious, in part because the high heat partially browns the egg white, which gives it additional flavors. You can alter the flavor of the egg with the fat you use—olive oil, for instance, or whole or clarified butter, rather than neutral vegetable oil.
Cooking fried eggs can be tricky. When you use a plain steel pan, the cooking surface must be immaculate, you must use plenty of oil, and the pan must be very, very hot—fail in any of these requirements and the egg will stick. Nonstick pans are most convenient and allow you to cook the egg at lower temperatures, and they are more easily flipped for over-easy. To avoid flipping but to ensure that the white is set, the pan can be covered and removed from the heat to finish cooking. A well-seasoned cast iron pan is a good choice for frying eggs.
Hard-cooked: Hard-cooked or hard-boiled eggs have numerous culinary uses, whether as a convenient nutritious snack, chopped and tossed with a yolk-emulsified sauce (aka egg salad), or as garnish. There’s also the clever deviled egg, a technique that cooks the egg, separates the white and yolk, and then puts the egg back together in more tasty and elegant form.
When hard cooking eggs, it’s important to stop their cooking when they are done to prevent the yolk’s turning a drab, sulfur-smelling green. The yolk of a properly hard-cooked egg is a uniform, sunny yellow. To achieve this effect, place the eggs you’re cooking in a single layer in a pan and cover them with about 2 inches of cold water. Bring the water to a boil, remove from the heat, cover the pot, and set a timer for 12 minutes (some books recommend a shorter time, others a longer time—the time can vary depending on the size of the eggs and the number of the eggs, but 12 minutes is a good starting point; observe your eggs and make adjustments accordingly). Remove to an ice bath and chill thoroughly. Some people like to crack the eggs as they go into the ice bath, which facilitates peeling them and may also reduce the chance of the yolk’s discoloring. If you’re going to be peeling them right away, this is advisable.
Baked: Eggs can be baked in two satisfying ways, shirred and coddled. These eggs are served as individual items, not as garnish. To make a shirred egg, crack the egg or eggs into a buttered ramekin and cook over medium-low heat until the bottom is set. Finish the egg in a 350°F oven for a few minutes. Customarily a little cream is poured on top (and perhaps some Parmigiano-Reggiano or whole butter) to enrich the dish and mollify the heat.
While some refer to coddling as boiling eggs in their shell for a couple of minutes, a coddled egg can also refer to an egg cooked in a ramekin or container, covered, in a water bath, like a custard. This can then be seasoned with a flavorful fat such as butter or an excellent olive oil.
One specialized whole-egg preparation should be noted—preserved eggs. Eggs can be preserved with salt and with vinegar. Eggs that have been hard-cooked can be pickled in an acidic liquid. And salt-cured eggs are part of some Asian culinary traditions, of which the “thousand-year-old egg” is an example.
It should be noted that in addition to being great items on their own, eggs cooked whole this way are excellent garnishes. Most are familiar with hard-cooked egg chopped or sliced and served in salad. But a fried egg on a salad is excellent; a poached egg on a salad is a classic French custom. A fried egg on a ham and cheese sandwich can’t be beat. It’s an excellent sandwich ingredient on almost any sandwich, in fact. A whole egg dropped into piping hot soup is almost never a bad idea. A poached egg used as a garnish for steamed asparagus (and a nice beurre blanc) would make an elegant appetizer-sized course or light lunch. When in doubt in the kitchen, look to the egg, it will rarely fail you.
Cooking eggs whole but blended, free-form (scrambled eggs) or structured (omelet):
After the chicken breast, scrambled eggs are probably the most overcooked item in America (followed by the pork chop). Properly scrambled eggs are moist, delicate, glistening; they should even have a liquidy element to them, as if they’ve been lightly sauced.
Begin by combining the eggs completely, whipping with whisk or fork until no clear white can be seen. The egg mixture should be uniform in color and texture.
As a rule, eggs always respond better to gentle heat—high heat makes them rubbery and dry. If you use a nonstick pan, eggs can be scrambled over low heat in butter. The more stirring you do, the finer the curd; curd size is a matter of taste.
If you don’t have a nonstick pan, or a well-seasoned iron pan, you may need to use a higher heat to prevent the egg from sticking and browning; if this is the case, you’ll need to start them on the high heat, shaking the pan and stirring as soon as the eggs are in the pan, and then finish them off the heat, stirring continuously.
For an omelet, eggs are scrambled—continuously stirred—at the outset to achieve fine curd, allowed to set, then rolled from the pan. A seasoned pan or nonstick pan is helpful; using a clean steel pan is a little more tricky, in which case the same rules apply as for scrambled eggs in a steel pan. Omelets should be a uniform bright pale yellow, not browned, very moist, not dry. Omelets can contain cheese or cooked vegetables, though they shouldn’t be overstuffed; when using cooked vegetables, make sure these are very hot so that they may finish cooking the egg after it’s rolled. An omelet can be given a lovely sheen by finishing it with a bit of soft whole butter on top.
A thoroughly whisked egg can also be poached to interesting and tasty effect. Simply add it to barely simmering water until it’s cooked, then strain it, and season with salt, pepper, and butter.
The egg, separated:
Separated, egg whites and yolks are rarely cooked on their own. Whites are sometimes deep-fried into Styrofoam-like chips, and some people eat omelets made with whites only (why anyone would, I’ve yet to fathom). Egg whites, sweetened and whipped to peaks, can top a lemon pie (among numerous other dishes); this meringue is typically colored by being browned briefly in the oven but the egg white is raw.
Raw eggs can be used to great effect, in eggnog, for instance—the liquid is enriched with raw yolk, sweet fluffy meringue is folded in. A raw egg can fortify a milkshake with flavor and nutrition. But raw whites are not delicious on their own. Yolks, on the other hand, are; they’re delicious as a garnish on just about anything. The yolk is like a ready-made sauce—on a hamburger, grilled steak, or raw tartare.
A note about eating raw eggs. Factory chickens, that is battery chickens caged indoors in the tens of thousands in long coops, can be crawling with salmonella and other bugs, so it’s not a good idea to serve these raw or even poached if you need to be careful (if you’re serving the very young or very old). It is always advisable to use organic eggs or eggs from pasture-raised chickens when serving them whole with a runny or raw yolk, or when using a raw yolk, as for a mayonnaise. It’s worth the extra expense from a health standpoint, flavor standpoint, chicken standpoint, and environmental standpoint.
The egg as tool:
Eggs are so gentle and delicate in flavor that they pair beautifully with countless meats, vegetables, and grains. A custard (milk or cream and egg) alone is wonderful, but a custard can also hold other things, as in a quiche Lorraine, bacon and onion suspended in the smooth concoction that sets delicately when gently cooked; other preparations—frittatas, soufflés, egg salad, French toast, not to mention their many uses as a garnish—describe felicitous ways the egg joins other ingredients.
But perhaps the most important topic in the study of the egg is its use as a tool. It can enrich, thicken, emulsify, leaven, clarify, and even color.
Whipped egg can be brushed on pastries and doughs to create deep and appealing golden brown color under heat. Egg whites when added to a cold cloudy stock will, when that stock is heated, form a net that clarifies the stock as it congeals and rises to the surface. Egg shells have routinely been added to stocks being clarified, though most chefs who use them are rarely aware why this may be more than a chef’s myth; in fact, some food science experts believe the alkalinity that shells add to a stock enhances the egg white’s capacity to clarify.
Egg yolks will become thick when whipped over gentle heat, and thicken the liquids that contain them, resulting in such preparations as zabaglione and lemon curd, savory sauces, puddings, and custards to be turned into ice cream.
Another egg yolk technique is called a liaison—cream and yolk are combined and added, typically, to a stew to enrich it (but it has negligible thickening powers).
The most dramatic uses of the egg as a tool, though, and the yolk and the white perhaps vie for supremacy in their separate effects, are to emulsify and to leaven.
The egg yolk’s capacity to turn clear oil into an opaque, solid cream results in some of the most pleasurable sauces known. The yolk is the linchpin of hollandaise, béarnaise, mayonnaise, and aïoli, sauces whose very presence transforms (often upstages) the meat or vegetable it accompanies.
An emulsion happens when oil is mechanically split into infinitesimal orbs that remain separated by continuous sheets of liquid; the lack of movement and the many bonds created make the oil both stiff and opaque. When the orbs break through these sheets and combine into one big mass, collapsing into soup, the sauce is broken. The molecule responsible for keeping these miniscule orbs from coalescing with their brethren is called lecithin, which is half oil soluble and half water soluble; it embeds half of itself into an oil droplet, while the other half remains in the water “phase” of the emulsion, preventing other miniscule orbs from connecting and coalescing and amassing and breaking the sauce.
The result of a properly emulsified sauce is a lesson in the power of texture to convey flavor and pleasure. A good hollandaise, or a fresh mayonnaise, is a thing of beauty. A broken hollandaise is not. A broken mayonnaise cannot be served. The emulsified sauce is first about texture; combined with a great flavor, whether it’s simply lemon juice, or garlic and basil, or tarragon, shallot, and vinegar, the pleasure of an emulsified sauce is unmatched by any other sauce, indeed by most foods period.
Traditionally, clarified butter is used for the emulsified butter sauces, and this does result in a very elegant flavor, but whole butter (itself an emulsion) can be used as well. For a neutrally flavored sauce, mayonnaise, which is seasoned with salt and lemon juice, or a fresh vegetable or canola oil should be used. For aïoli, some olive oil. If you want to make an emulsified vinaigrette that is very stable, an egg yolk can be added. The freshness of the fat is critical—if you use old oil or rancid olive oil, the off flavors become magnified. Always use the freshest best-tasting fat possible. And the fat need not be relegated to one of these three, either. The egg yolk can turn any clear fat into an unctuous pleasure. To an egg yolk mixed with a reduction of minced shallot and wine vinegar, for example, one might whisk in clear warm bacon fat for a bacon-shallot emulsion that can be served atop a poached egg.
The consistency of the emulsified sauce—whether a béarnaise sauce or an aïoli—should be as stiff as mayonnaise. Unless you don’t want it to be that stiff. It can easily be thinned with water or cream. If you fold whipped cream into an emulsified butter sauce it’s referred to as a mousseline.
Egg white’s capacity to contain countless miniature air bubbles (a mirror image perhaps of egg yolk’s capacity to separate oil in countless miniature droplets) allows it to leaven many preparations, whether raw (as with a mousse), or cooked (everything from soufflés, both savory and sweet, to sponge cakes). This egg-as-leavener has even more uses than the yolk does as an emulsifier, and is more widely used.
The eggless kitchen is difficult to imagine. Eggs are everywhere in cooking, in myriad forms. It’s important to acknowledge and understand the powers of the egg. I said above that the egg will rarely fail you; a more complete expression of the same idea is this: you will fail it more often than it fails you, and the more capable you are with the egg, the more capable a cook you will become.
By Michael Ruhlman in "The Elements of Cooking", Scribner (a division of Simon & Schuster), New York, 2007. Adapted and illustrated to be posted by Leopoldo Costa.