White-Bean Puree With White Truffles

1 pound dried white beans, preferably cannelini or navy beans
1 medium onion, halved
1 sprig fresh sage, or 1 teaspoon crumbled dried sage leaves (do not use powdered sage)
1 clove garlic
¼ cup extra-virgin olive oil
½ ounce white truffle or 2 tablespoons white truffle paste

Nutritional Information
- Nutritional analysis per serving (6 servings)
  347 calories; 9 grams fat; 1 gram saturated fat; 6 grams monounsaturated fat; 1 gram polyunsaturated fat; 49 grams carbohydrates; 13 grams dietary fiber; 2 grams sugars; 18 grams protein; 14 milligrams sodium

6 to 8 servings

Cover the beans with water, and soak overnight. Or use the quick- soaking method: Cover the beans with water, bring to a boil, and boil 2 minutes. Remove from the heat, and set aside for 1 hour.
Drain the beans and discard the soaking water. Place the beans, onion, sage, garlic and oil in soup kettle. Add fresh water to cover. Bring to a boil, lower the heat, and cook, covered, at a bare simmer until the beans are very soft, 40 minutes to 2 hours, depending on the age of the beans. Keep a teakettle of water simmering, and as the beans absorb the liquid, add more water, little by little. The beans should always be covered by liquid but never swimming in it.
If fresh sage is used, remove the sprigs and discard. Place the beans and liquid in a food processor, and process until very smooth. If using fresh white truffle, scrape half into the puree, and continue processing until well blended. Serve the puree immediately, with the remaining truffle shaved over the surface. If using truffle paste, puree the entire amount with the beans just before serving.