Ruhlman's Twenty (7 page)

11
/Rinse the salmon under cold running water to remove the cure.

12
/Slice the salmon as thinly as possible.

WATER IS SO UBIQUITOUS, SO PREVALENT
in cooking, that many books, magazines, and newspapers don’t even include it as an ingredient in recipes—”on the assumption that our readers have a ready supply,” according to the
New York Times
editor Nick Fox. This assumption implies that if you didn’t have unlimited water, you would be fatally handicapped in your cooking—an accurate implication. What I like about the
Times’s
assumption is that it both calls attention to and obscures the fact that water is one of the most important ingredients in the kitchen.

In its omnipresence, its seemingly unlimited nature, we tend to overlook it for what it is: a miracle ingredient we use every day. Water, like salt, is essential to the maintenance of life, and in the kitchen it is equally important as both ingredient and tool.

H
₂
O behaves in radically different ways from other molecules. When it freezes, for instance, it doesn’t grow more compact, but becomes less so; it opens up so that it floats in liquid water. Frozen water can skip the liquid phase and move straight into the gaseous phase (this is how wet clothes hung on a line in freezing temperatures dry). You can change water’s shape, but not its volume, which has a consistent weight. Water’s density, its compactness—the strength of the two hydrogen atoms bonded to an oxygen atom and the intense attraction of one H
₂
O molecule for another—makes it an exceptionally efficient cooking medium. Water holds an extraordinary amount of thermal energy and conveys its temperature very quickly to food. You’d have to leave your hand in a 200°F/95°C oven for a long time before it became uncomfortable. Sticking your hand in the same temperature water would scald your skin in seconds.

The density of water is the reason that it is relatively slow to heat up, contains so much energy, and is also slow to cool down. This density allows fat to rise to the surface of a soup or stock and be skimmed from the top. One of water’s most important attributes is that it boils at 212°F/ 100°C. It can exist simultaneously as liquid and solid at 32°F/0°C, which is how cold you want an ice bath, the water and ice. Add salt to such an ice-water mixture, and you lower its freezing point, making it colder and thereby allowing you to chill food very fast or to transform a custard into ice cream. When ice melts, it absorbs energy; plunge hot food into an ice bath, and that energy speeds out of the food and into the water. (Imagine plunging something hot into freezing-cold oil; it wouldn’t get cold nearly as fast as if you were to plunge it into water of the same temperature.) When water turns to vapor, it takes energy with it and so cools our bodies when we sweat and cools liquids held in a porous vessel. When water condenses on a cold surface, it gives up that heat.

When water gathers enough energy, it will not be able to maintain its volume, and it jumps into vapor, which can contain even more energy than water in liquid form. Therefore, vapor, or steam, can be hotter than 212°F/100°C and make for an efficient cooking tool.

When you understand the behavior of water, you can begin to have more control over it, and having control over a ubiquitous ingredient and tool makes you a more efficient cook. To understand cooking, develop an intuitive sense of the properties of water, and identify and learn its main uses.

Three properties make water a powerhouse ingredient in the kitchen: water is extremely dense; its chemical composition—those strong hydrogen bonds—makes it good at pulling other molecules apart; as a liquid, it cannot rise above 212°F/100°C.

We use water as a cooking tool in five distinct ways:

1
/ As a direct cooking medium (boiling, steaming, poaching)

2
/ As an indirect cooking medium (water bath)

3
/ For cooling and freezing

4
/ In the form of a brine

5
/ As a tool for extracting flavor from food and serving as the medium for flavor

As a direct cooking medium, water has a variety of applications. We boil two things, green vegetables and pasta. Yes, we can and sometimes do boil lots of things, but these two categories of food require the fastest, moistest cooking. If you were to poach pasta or green vegetables, the outside would become overcooked long before the inside was done. Vegetables can be roasted, but because air is much less dense than water, roasting takes longer; it’s also hotter and so has browning effects. The fast cooking of green vegetables helps you take advantage of their deep green color, which is part of their appeal.

Boiling does not involve a lot of technique, but it does involve some technique. The most common error people make when they boil food is using too little water. When you’re in a hurry, or have a lot going on in the kitchen and are not thinking, it’s easy to choose the wrong pot or to put too little water in it. Boiling in abundant water is the key to good boiling. The energy that water can contain, not the volume of water, is what matters. The more energy you’ve built up, the faster you can cook what you’re boiling, and the faster it cooks, the better it is. If you put in more food than the water has energy to give it, the food poaches in water that must now gather up more energy to give to the food. Ideally, you should have so much water relative to the amount food that the water doesn’t lose its boil when you put the food in it.

Thomas Keller is such a fierce advocate of this kind of boiling for green vegetables that he has instructed cooks at his French Laundry restaurant to recook an entire batch of fava/broad beans added to water that lost its boil. He wants the water to be heavily salted and at a vigorous boil (salted water can get even hotter than unsalted water). This is something to keep in mind when boiling green vegetables. If you don’t have big enough pots, try to get the water temperature back up as fast as possible by covering the pot. (Be sure to remove the cover as soon as the water returns to a boil. If you don’t, you can easily overcook and discolor the vegetables.)

Pasta, too, should be cooked in abundant water as quickly as possible.

We can also steam green vegetables above boiling water. Although steam can be hotter than boiling water, it is less dense; therefore, steaming can be less predictable than boiling, which is always, and infallibly, at 212°F/100°C. Steamed green vegetables and boiled green vegetables are nearly identical, but I find boiling more consistent than steaming. Doughs and some other grain preparations benefit from steam, as the intense moist heat doesn’t completely saturate the product. Chinese buns and dumplings, for instance, are excellent steamed, and couscous is traditionally steamed over the stew it will accompany.

We poach food that benefits from moisture but does not benefit from speedy cooking or is so delicate that the high temperature or agitation of boiling water, or both, would damage the food. We poach fish, eggs, delicate mixtures of ground meat or seafood, root vegetables, and legumes. Poaching is such an important and distinctive use of water that I devote a whole chapter to it
(See technique #17)
.

When we use water as an indirect cooking device, there is a barrier between the water and the food, most often some kind of vessel set into hot water. A water bath is simply a roasting pan/tray or other pan partly filled with hot water. Using a water
bath takes advantage of water’s capacity for gentle heating to set custards and to cook other egg-based dishes and other preparations such as a pâté en terrine (pah-TAY ohn teh-REEN), meat loaf in a terrine mold. Set ovenproof dishes in this water bath and their contents will cook at a temperature of 180° to 200°F/83° to 95°C. Part of the advantage of a water bath is that it is continuously evaporating; as the water becomes vapor, it takes heat away with it. So even as the water bath is heated by the oven, it is cooled by evaporation, ensuring that very moderate heat surrounds whatever you’re cooking. Proof of the power of the gentleness of water-bath cooking is that a cheesecake baked in an oven typically cracks as it cools; a cheesecake cooked in a water bath in the oven typically will not.

The capacity of water to absorb thermal energy makes it an effective cooling device. One of the main things a cook does is control temperature, and water is a great temperature controller. Not only does it heat food to a specific temperature. It also can drop a food’s temperature rapidly. We frequently need to cool food
(technique #20),
usually to halt its cooking. When we remove food from the heat, the latent heat within the food keeps cooking it. That’s why a thermometer inserted into a roast beef or leg of lamb may initially read 130° to 140°F/54° to 60°C but will continue to rise for ten minutes or so after the meat is removed from the oven. This is also true for green beans, custards, cakes, anything that you heat.

Sometimes we want to control the heat by taking food to a certain temperature, then stopping the cooking
fast.
When green beans are exactly right—bright, bright green and completely tender—we can plunge them into ice water, which sets the color and tender texture. When we whisk a mixture of eggs, sugar, and cream over heat until it thickens to the perfect
consistency, we strain the mixture into a bowl set in an ice bath to preserve the texture and prevent the eggs from cooking further.

Water is also used to freeze food. When salt is added to ice and water, the freezing point of water is lowered. Without the presence of salt, water and ice will remain at around 32°F/0°C; add abundant salt, and the temperature can drop many degrees below that. Salt (or anything dissolved in the water) inhibits the formation of ice. The salt makes it harder for the water molecules to attach to the ice because it gets in the way. Therefore, the water has to be even colder than the 32°F/0°C it needs to attach itself to the ice when there’s no salt getting in its way. This is how we freeze custards into ice cream, and flavored waters and juices into sorbets and ices.

Water is an excellent carrier of salt. When water contains enough salt, it becomes a brine. A brine not only seasons food to its center; it can also make food juicier. Salt changes the cell structure, allowing the cells to take in more water. Brine also flavors food. Aromatic seasonings in a brine get carried into the meat as the salt works its osmotic wonders.

Finally, and perhaps most important of all, brine preserves food by disabling bacteria that cause spoilage. I say “most important” because brines were fundamental to the advancement of civilization, allowing explorers to travel long distances. Pork, held in a strong salt solution, would keep indefinitely. Beef could be preserved by corning it—that is, by brining it. We continue to make corned beef and pastrami, not because our survival depends on it, but because they are so delicious.

Brines are really about the salt, not about the water; the water facilitates the salt.
(See the brining.)

Perhaps the most important and least appreciated—or least examined—way we use water is to pull flavor from other ingredients and to hold that flavor and give it shape.

When most foods are heated in water, the water takes on the flavor of the food. It’s remarkable when you think about it. The same thing doesn’t work with oil, or with any other nonwater-based fluid. What gives water this power are those hydrogen atoms, which are so muscular in their efforts to bond, to pull things apart, to dissolve other compounds. If you pour some water over sliced onion and carrot, and heat the water, you’re going to have water that’s sweet and delicious from these very sweet root vegetables. Caramelize the onions deeply, pour water over them, heat the water for about 20 minutes, season with salt and pepper and a splash of sherry, and you’ve got a delicious onion soup. Put some onions in a pan used to roast a chicken, add scraps from the roasted chicken such as the wing tips, cook the onions a little, pour water over them, cook the water until it’s gone, and then add a little more water (see
Pan Sauce for Roasted Chicken
for specifics), and you’ll have a flavorful sauce to serve with your chicken.