Step 1

Soak beans overnight in 2 quarts water. (Alternatively, place beans and 2 quarts water in a large pot. Bring to a boil. Boil for 2 minutes. Remove from heat and let stand for 1 hour.) Drain the beans, discarding soaking liquid.

Step 2

Combine oil, mustard seeds, chili powder, cumin and cardamom in a 5- to 6-quart Dutch oven. Place over high heat and stir until the spices sizzle, about 30 seconds. Add onions, mushrooms, tomatillos and water. Cover and cook, stirring occasionally, until the vegetables are juicy, 5 to 7 minutes. Uncover and stir often until the juices evaporate and the vegetables are lightly browned, 10 to 15 minutes. Add broth, tomato paste and chipotles; mix well.

Step 3

Place the beans in a 5- to 6-quart slow cooker. Pour the hot vegetable mixture over the beans. Turn heat to high. Put the lid on and cook until the beans are creamy, 5 to 8 hours.

Step 4

Garnish each serving with cheese, a dollop of sour cream and a sprinkling of cilantro. Serve with lime wedges.

Step 5

Stovetop Variation:

Step 6

Total: 4 1/2 hours

Step 7

In Step 2, increase broth to 8 1/2 cups. Omit Step Add the beans to the Dutch oven; cover and simmer the chili gently over low heat, stirring occasionally, until the beans are creamy to bite, about 3 hours.