Three 15 1/2 ounce cans black beans (about 4 1/2 cups), rinsed and drained
1 cup drained canned tomatoes, chopped
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
a 16-ounce can pumpkin puree (about 1 1/2 cups)
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