Sort beans for debris, then rinse. Bring beans and 2 quarts water to a boil over high heat in a 5- to 6-quart pan. Cover, boil for 2 minutes, and remove from heat. Beans are ready to cook after soaking for 2 hours, but are more digestible after 4 hours. Drain and rinse beans.
In a 6- to 8-quart pan, bring 7 cups water and beans to a boil. Reduce heat; simmer, covered, 45 minutes.
Meanwhile, in a 10- to 12-inch frying pan over medium-high heat, stir bacon often until browned, about 5 minutes. Lift bacon from pan; drain on towels.
Discard all but 3 tablespoons fat from pan. Add chilies and onion; stir often until onion is brown, about 5 minutes. Stir in brandy.
Add mixture to beans, plus bacon, salt, and pepper. Simmer, covered, until beans are tender, about 30 minutes.
Ladle soup into bowls. Spoon black beans on top of soup. Garnish with cilantro.