Active time: 10 min Start to finish: 2 hr

Ingredients

　　1/4 lb dried black beans (2/3 cup), picked over and rinsed

　　1 small onion, finely chopped (1/2 cup)

　　2 fresh cilantro sprigs

　　1/2 tablespoon olive oil

　　6 cups cold water

　　1/4 teaspoon salt, or to taste

　　Bring beans, onion, cilantro sprigs, oil, and water to a boil in a 2-quart heavy pot. Reduce heat and simmer, partially covered, until beans are just tender, about 1 1/4 hours. Add salt and simmer, uncovered, until liquid is evaporated to just below level of beans. Season with salt and discard cilantro sprigs.

　　Cooks' notes:

　　• If you don't have time to cook dried beans, rinse and drain a 19-ounce can of cooked black beans. Cook onion in oil in a small heavy skillet over moderately low heat, stirring, until softened, then stir in beans, cilantro, salt, and 1/4 cup water and simmer, stirring, until beans are heated through. • Beans can be cooked 1 day ahead and cooled, uncovered, then chilled, covered. Reheat before serving.