How do you make a carrot taste more like a carrot and yet taste completely original at the same time? Turn it into a cold summer soup--a bright, fresh, satiny elixir, a spoonful of which tastes like a whole gardenful of carrots in your mouth.
Using the same technique, you can similarly transform peas or favas or corn or zucchini or peppers, broccoli, cauliflower--just about any edible plant.
Even better, the cold soup technique is one of the easiest things you can learn in the kitchen, and it uses summer flavors at their peak.
Here’s how it works: Choose your vegetable, then cook it, blend it, adjust the consistency with a liquid if necessary, season and strain.
The logic is simple. You simply bring a vegetable to its peak of flavor by cooking it in the same manner you would use when serving it hot.
Green vegetables--peas, broccoli and asparagus--you cook in a big pot of heavily salted, vigorously boiling water, then shock in ice water.
Root vegetables such as carrots, turnips and beets, you glaze--that is, cook in a little bit of liquid and butter until that liquid evaporates and the vegetables become coated with the shiny, sweet reduction of the cooking liquid.
Cauliflower and sweet bell peppers are exquisite poached in cream.
Those vegetables that are normally served raw you need not cook at all--cucumber or tomato, for example.
Because vegetables are composed largely of tasteless cellulose and fiber, you must next blend the heck out of them and then strain them through a fine meshed sieve called a chinois. The chinois, now widely available in fine cooking stores, is critical to a clean, luxurious texture.
The final step in all cooking is seasoning. You’ll need salt, of course, but with these soups, you will typically add some kind of fat, as well, most often olive oil. Sometimes you will also need an acid. And that’s all there is.
Here is an example of a simple summer soup. Peel and seed a cucumber, cut it into pieces, then puree till smooth in a blender, adding a healthy pinch of salt and a tablespoon of extra-virgin olive oil, and then strain it through a chinois. That’s your soup. Add a sprig of dill if you’re feeling clever. It’s summer in your mouth.
As always there are keys to finesse. Any dish using so few ingredients can only be as good as those ingredients. Choose the best. If your vegetable is pale and flavorless, your soup will be too. If your olive oil is harsh or rancid, your soup will be unpleasant to eat.
As you become comfortable with the cook-blend-season-strain method, you will find that various vegetables benefit from slight alterations in ingredients or technique.
Peas and fava beans might be enhanced by truffle oil rather than olive oil. For a pure corn soup, blend, strain and then cook, allowing the starch from the corn to thicken the soup. For a zucchini soup, blanch a whole zucchini, seed it, wring out as much water as possible, then blend-season-strain. Dried white beans, properly cooked, make a wonderful cold summer soup, seasoned with mint and olive oil.
Here’s another “secret”: many of these cold soups are delicious hot too. And one more: pour a little of the soup onto a plate and it’s a dazzling sauce for a main course.
We haven’t even gotten to fruits and dessert soups! Berries, peaches and pears work the same way. Replace the fat with simple syrup (equal measures of sugar and water cooked together), add a little lemon juice and season with vanilla bean or even black pepper. Perfect the method and you have an almost infinite repertoire of extraordinary soups at your fingertips.
These cold soups are not only simple, they are at the same time the essence of great cooking--demanding that we choose a single ingredient at the peak of its ripeness and bring it, through careful manipulation and with as few supporting ingredients as possible, to the height of its flavor. The essence of itself.
Keller is chef at the French Laundry in the Napa Valley. Ruhlman is author of “The Soul of a Chef” (Viking, $26.95). Keller and Ruhlman are co-authors of “The French Laundry Cookbook” (Artisan, $50).