We tend to think of sauce as something we pour over something else just before serving it, but practically speaking, sauce is any seasoned fat, acid, cooking liquid, juice, plant puree, or combination thereof, that we add to a main ingredient to enhance it, and it’s helpful to the cook to think of it in this fundamental way.
Yes, it’s the tomato sauce on the pasta, the beurre noisette on the sautéed trout, the ketchup on the hamburger, the chocolate on the profiteroles. But the mayonnaise that enriches and binds a tuna salad is its sauce; a quenelle of olive tapenade on a grilled duck breast can serve as its sauce. The vinaigrette is a salad’s customary sauce. Braised items help to create their own sauce. A poached egg can get away without having a sauce because it contains its own, but add a spoonful of beurre blanc and it becomes an exquisite dish. In a classic chicken chaud-froid (hot-cold), a cooked sauce is spooned over cooked and chilled chicken so that the sauce completely coats, then solidifies on, the chicken—a fancy way to sauce food. Soup is little more than main ingredients in an abundance of sauce. A crème brûlée is in effect nothing more than a seasoned dessert sauce cooked to set the proteins.
Sauce can transform a dish or a meal from good to great but should never call attention to itself—it’s always in the service of something else, and as such constitutes an unusual culinary specialty in its own right. This is why in the French brigade system, which divides chefs into various departments, the saucier is often the most talented cook in the kitchen, the magician and sorcerer. From the beginning of the meal (mustard with the charcuterie platter) through to dessert (ice cream on pie, or raspberry puree with a chocolate torte), there’s almost no dish that doesn’t benefit from some form of sauce.
From the cook’s standpoint, sauce is an idea and a function, and the best are integral to and inseparable from what they accompany. While they can be categorized in several ways, again, they generally fall into one of three categories: stock based, fat based, and plant based (fruit or vegetable).
Stock Refined
The pinnacle of sauce making is reached in the stock-based sauces, not so much because they taste better than any other sauce, but rather because they require the most effort and are distinguished by numerous elements of finesse. And of the stock-based sauces, the brown sauces are at the top of the heap.
Brown sauces are veal-stock based; any meat-and-bones mixture can be roasted and, with caramelized vegetables, make a fine brown sauce, but in the sauce pantheon, the true brown sauces begin with veal stock.
Veal stock was once turned into espagnole sauce; that is, it was thickened with a brown roux, and fortified with more caramelized mirepoix. This could be further refined into a classical demi-glace by being combined with more veal stock and reduced. Both brown sauce, the mother mother sauce, and classical demi-glace can be transformed into myriad sauces à la minute because they are rich with neutral meat savorines and vegetable sweetness, and they have already developed an excellent saucelike consistency to add to whatever juices and aromatic vegetables they will enhance.
If even the most timid cook has some espagnole on hand, family and friends may think him a genius saucier, because any pan he adds it to seems transformed into a magical pan—with some minced shallot, mustard, fresh herbs, and mushrooms, suddenly the plain roasted chicken, the blasé pork loin, or the boring and expensive filet mignon will take on a deliciousness that astonishes, given the small fulcrum of the veal-stock-based mother sauce (which, truth be told, doesn’t taste all that appealing on its own—part of its magic).
Any stock can be fortified and prethickened with a roux this way—when it’s a white stock (chicken or fish) it’s called a velouté—with excellent results, provided you take time to skim the skin off the surface as it forms and the flour cooks out.
Even milk can be thickened this way to make a sauce called béchamel, a concoction of surprising versatility. Here, milk is like a ready-made stock, easily thickened and seasoned to become the base of any number of great cream sauces for pasta, white meat, fish, and vegetables.
Roux-thickened sauces have gotten a bad rap because of their association with heavy antiquated or badly prepared French food. This is too bad because a roux is potentially the most elegant and refined way of thickening a sauce. Stocks thickened only by reduction can feel gluey, and stocks thickened by a pure-starch slurry, such as with cornstarch, can become diluted by the starch and take on a gelatinized-starch texture. A sauce thickened with a roux, one in which the base sauce has been properly cooked and skimmed, has a rich flavor, luxurious body, and a lightness on the palate.
The only problem with roux-thickened sauces is that they require more work. To make a veal stock one day and then further to make a brown sauce from that stock will take up a big chunk of a second day. Because milk is at the ready, béchamel sauce may be the most practical of the roux-thickened sauces for the home cook. For committed cooks, mother sauces and their derivatives are worth doing, as the process contains many lessons for the cook, not least of which are the pleasures of eating a great sauce. Also, mother sauces freeze well, so a big batch can be divided into small quantities for future use.
Practically speaking, any stock can be reduced, fortified with elements of the meal—additional aromatics, bones and meat trim, herbs, seasonings—to make fine stock-based sauces. Veal is the easiest and most versatile of all the stocks. It can be served as is or thickened with a slurry (cornstarch and water).
Don’t ignore water as the fundamental stock and sauce base. No, it doesn’t have any flavor or body of its own, but it picks up flavor very quickly and so last minute pan sauces can be fast and easy even if you don’t have stock on hand. Water is certainly superior to canned broths. If you roast a chicken in a pan, for instance, you can put together a delicious sauce while it rests using water to create a basic stock and sauce right there. Remove the chicken to a cutting board, pour off excess fat from the pan and reserve any skin stuck to the pan, the wing tips, and the neck, gizzard, and heart if you have roasted them with the chicken. Set the pan over high heat, add a cup of chopped carrots and onion, and cook briefly. Deglaze the pan with white wine and cook it down till the pan is nearly dry, then cover the vegetables and chicken trim with water and cook over high heat. Season with salt and pepper. You will have a flavorful jus in a few minutes that can accompany the chicken.
If you have time, let all the water cook off to brown the sugars released into the water from the vegetables, add more water, and cook this down again.
For a more refined sauce, strain it into a small pan, swirl in some butter, some fresh herbs, or some mustard, to further enhance it.
Would such a sauce be deeper and richer if you used a good chicken or veal stock instead of water? Yes. But can you make a good quick sauce without stock? Absolutely, and it will be far superior to one that you made using a store-bought stock or broth instead of water. Finally, derivative sauces and meat-based sauces are volatile.
There’s a reason they’re finished à la minute. If they’re made and held, their flavor becomes dull. They need to be completed just before serving for the freshest and most vibrant flavor. Leftover sauce can be reused after it’s been refrigerated, but it needs to be refreshed with additional stock and straining.
Fat’s Great Transformation: The Emulsified Sauce
Fat is by far the easiest material to transform into sauce because it’s virtually a sauce already—it’s rich and luxurious at the outset, and all the cook must do is flavor it and adjust its consistency. Consistency is extremely important in fat-based sauces. Canola oil by itself is not enticing, but whip it into a mayonnaise and the consistency alone is appealing. Flavor, which makes the fat distinctive and satisfying, comes from the usual sources: acid, aromatics, spices, and salt.
It’s also the easiest sauce to give to a dish. Butter on chicken or steak is excellent by itself, a good olive oil mixes perfectly with the sweetness and acidity of a tomato from the garden.
Butter offers its own category of sauces in what’s called compound butter, that is butter flavored with fresh herbs, aromatics, and acid, and put directly on the food. When butter is heated, the solids separate from the clear fat and brown, the flavor deepening into nuttiness; herbs and acid finish it to make a delicious all-purpose sauce.
But when the cook applies some energy and craft to fat, emulsifying it—transforming it from liquid to thickly creamy—sauces of great distinction result, sauces that may be more satisfying than any other category of sauce.
There are two primary fats used for emulsified sauces: oil and butter. Oil emulsifications are mayonnaise or mayonnaise variants. When the fat is butter, the result is referred to as an emulsified butter sauce, such as hollandaise. Both use egg yolk as the means for emulsifying a lot of fat into a little bit of water. For mayonnaise-style sauces, oil is whipped into raw egg yolk (and a few drops of water and/or citrus juice and seasoning). For emulsified butter sauces, the egg yolk mixture is cooked and the butter (clarified or whole) is then whipped into the egg mixture.
The ratios for both are fairly standard though they can be varied according to your tastes and style. For mayonnaise, use one yolk for each cup of oil. For butter sauces, the classical ratio is three yolks for eight ounces of butter (though the extra eggs are more for texture and richness than for the emulsification).
The principles are mainly the same. For a mayonnaise, the liquid (lemon juice and water) is combined with salt so that the salt melts; this is combined with the yolk, then the oil is whipped in, at first drop by drop as the emulsion is formed, then in a thin steady stream as you whisk continuously. For the butter sauces, a reduction is used to flavor the sauce; a mixture of aromatic herbs, vegetables, spices, salt, and acid (vinegar and/or wine) are cooked and strained; this liquid is combined with the yolks in a pan or a bowl. The yolks are put over heat (typically a hot water bath to avoid overcooking the yolks) and are whipped as they cook. When they are cooked and foamy from whipping, the butter is slowly whipped in. The sauce can be finished with fresh herbs and aromatics.
Emulsified butter sauces and mayonnaises are delicious with all manner of meat, fish, shellfish, vegetables, and eggs. Mayonnaises, such as the garlic–olive oil aïoli, are especially good with meats, shellfish, and vegetables that are served cold.
There’s also a kind of eggless emulsified butter sauce that takes advantage of the fact that whole butter is already an emulsification of water, solids, and fat. Aromatic vegetables such as shallots or onions are cooked with wine till the liquid is reduced, then the butter is whipped in piece by piece. These sauces, called beurre blanc or beurre rouge depending on the wine used, are very easy and quick to make.
Likewise, there is an eggless oil-based sauce, heavily reliant on acid—the emulsified vinaigrette. Salt and mustard season one part vinegar, then three parts oil are mixed in. Because mustard has some emulsifying power, a stable emulsion can be achieved, though one that’s considerably looser than a mayonnaise. This is easiest to make using the power of a blender but an emulsified vinaigrette can be made the same way as mayonnaise.
Contemporary Sauces
American cooking has evolved dramatically during the past decade. So has the way we think about food. The definition of sauce is not relegated to those special preparations to spoon over meat and vegetables but instead should be described as a kind of continuum of flavor and texture that can range from solid (a compound butter) to waterlike (a nage) depending on the food it’s meant to elevate. A puree of tomatoes, cooked, has long been one of the main sauces, considered to be a mother sauce, but any vegetable puree can serve as a sauce.
An asparagus sauce—asparagus cooked, shocked, pureed, then seasoned with salt and lemon and enriched with butter as it’s reheated—is every bit as satisfying as a butter sauce on a white fish. It can be highly refined, thinned by straining or served thick and substantial.
What you are doing is simply transforming the consistency of the ingredient to turn it into a sauce. You are cooking the asparagus as you would if you were planning to serve it whole, right down to the salt, butter, and lemon juice. You can do this with any vegetable. Likewise, most fruits can be cooked, pureed, and strained for delicious dessert sauces.
Such preparations can be taken even further—they can be served as soup. In contemporary cooking often the line between soup and sauce is completely blurred. Broths can function as sauces, for meat and fish; vinaigrettes can be used like classical sauces, vegetable juices can be transformed into sauce. The definition of sauce is ever expanding.
As Americans travel more and American restaurant culture grows increasingly diverse, we are becoming familiar with a range of sauces from other cultures—Asian dipping sauces (based on fermented soybeans and fish, which represent a whole new category), South American chimichurri (in effect a vinaigrette-soaked herb sauce), to Mexican moles and Asian curries (often using pureed peppers, seeds, and nuts for flavor and body).
There’s no end to the world of sauces but they’re very easy to organize in your mind when you’re thinking about what sauce to combine with tonight’s dish. Indeed, sauce isn’t about anything more than flavor and seasoning. When you’re adding a sauce to a dish, you’re not doing anything more complex than seasoning it. Just as you season a dish with salt, not so that you can taste the salt, but to enhance the dish. Think of sauce as an elaborate form of salt. Which of course is what the word sauce means and derives from.
By Michael Ruhlman in "The Elements of Cooking", Scribner, New York, 2007. Adapted and illustrated to be posted by Leopoldo Costa.