Preparation

• In a medium frying pan over low heat, heat the butter and oil. Add the onions, shallots, and leek; cook, covered, for 20 minutes; uncover and cook, stirring often, until very soft and a deep golden brown, another 40 minutes. Add the broth and boil for 6 to 8 minutes to reduce slightly. Purée in a food processor and strain though a sieve or pass the mixture through a food mill. Season with salt and pepper to taste and add more broth if the sauce is too thick.

Carrot or Fennel Coulis: Omit the onions and add 1 lb. of carrots or fennel to the shallots and leek. Cook until very tender but not brown. For a richer sauce, use half cream and half broth.

Red Pepper Coulis: Roast or grill 3 to 4 red bell peppers until charred. Remove the stems, seeds, ribs, and charred skins. Purée in a food processor and strain though a sieve or pass the mixture through a food mill. Season with a bit of balsamic vinegar, deglazed pan drippings, or a bit of puréed canned chipotle chile. This is also good with poblano or Anaheim chiles in place of, or in addition to, the bell peppers.

Roasted Garlic Coulis: Cut off the top third of 3 heads of garlic, wrap loosely in foil, and roast at 400°F until soft, about 1 hour. Squeeze the garlic pulp from the skins and work it through a food mill or a strainer. Season with salt and pepper. Put the purée in a small saucepan. Add 1-1/2 cups broth or cream (or a combination of the two) and simmer until reduced to the desired consistency. Add a bit of extra-virgin olive oil for a smoother, creamier consistency.