Tomato Consomme

Tomato water may not sound like much, but it is an amazing ingredient. This intensely flavored clear liquid can be used by itself as a soup, or it can be part of a larger dish--a cooking liquid, a sauce or an aspic. At this time of year, when tomatoes are flavorful and abundant, it’s almost a crime not to test the water.

It couldn’t be simpler to make: Tomatoes are mostly water, and all you need to do is release that tasty liquid. Puree the tomatoes, wrap the puree in cheesecloth and then put it in a colander or hang it over a bowl to drip for a day.

It’s delicious unadorned, as in a simple consomme. But tomato water can be altered in countless ways. Serve it hot or cold. Reduce it to intensify the flavor. Season it with hot spices or sweet, fragrant herbs such as basil or tarragon. Tomato water is a terrific poaching liquid--try cooking some halibut in it, then reduce some of the tomato water, beat in some butter or olive oil, and finish it with some fresh chopped tomatoes and basil. Any lean white fish or chicken breast will work just as well.

Add gelatin to the tomato water along with minced jalapeno, cilantro or chopped Kalamata olives--whatever is on hand--and pour it into a ramekin to firm into a very elegant aspic--a cool intermezzo on a hot evening.

Or add just a little gelatin (and a pinch of cayenne) and the water will take on a sauce-like consistency, perfect with a salad of summer vegetables.

Beat in butter or olive oil and other seasonings or fresh herbs, and it can become an extraordinary pasta sauce.

For a while at the French Laundry, we served a first course that had a little fun with the idea of tomato water: the waiter put some finely minced jalapeno in the bottom of a chilled martini glass and then swirled in some icy tomato water. A cooked shrimp hung on the edge made for a very elegant “shrimp cocktail” that would be very easy to make at home.

You can go crazy with tomato water: Freeze it (it keeps for weeks), then shave it like an Italian ice and serve it with a minced cucumber, red onion and bell pepper as a gazpacho snow cone.

One important technical point: If you’re combining tomato water with other ingredients, it’s not necessary that it be perfectly clear, but for something like a soup or an aspic you need to clarify it. Bring the tomato water to a simmer, skim the solids that rise to the top, then strain the water again through a kitchen towel. You may need to further clarify it by decanting it (pouring off the liquid, leaving the solids behind) or by straining it through a coffee filter if particles continue to settle on the bottom.

Here’s one more idea: add it to champagne for the perfect summer cocktail. Such a simple thing, yet there’s no end to the invention.

Keller is chef at the French Laundry in the Napa Valley. Ruhlman is author of “Wooden Boats: In Pursuit of the Perfect Craft at an American Boatyard’ (Viking, $24.95). They are co-authors of ‘The French Laundry Cookbook’ (Artisan, $50).