Three 15 1/2 ounce cans black beans (about 4 1/2 cups), rinsed and drained (or equivalent homemade black beans)1 cup drained canned tomatoes, chopped (or fresh tomatoes) 1 1/4 cups chopped onion 1/2 cup minced shallot 4 garlic cloves minced 1 tablespoon plus 2 teaspoons ground cumin 1 teaspoon salt 1/2 teaspoon freshly ground black pepper 1/2 stick (1/4 cup) unsalted butter 4 cups beef broth about 1 1/2 cups pumpkin puree 1/2 cup dry Sherry 1/2 pound cooked ham, cut into 1/8-inch dice 3 to 4 tablespoons Sherry vinegar

Garnish: sour cream and coarsely chopped lightly toasted pumpkin seeds

In a food processor coarsely puree beans and tomatoes.

In a 6-quart heavy kettle cook onion, shallot, garlic, cumin, salt, and pepper in butter over moderate heat, stirring, until onion is softened and beginning to brown. Stir in bean puree. Stir in broth, pumpkin, and Sherry until combined and simmer, uncovered, stirring occasionally, 25 minutes, or until thick enough to coat the back of a spoon.

Just before serving, add ham and vinegar and simmer soup, stirring, until heated through. Season soup with salt and pepper.

Serve soup garnished with sour cream and toasted pumpkin seeds.