In a 5- to 6-quart pan over high heat, frequently stir bacon until crisp, about 4 minutes. Lift out with a slotted spoon and drain on towels. Discard all but 1 tablespoon of the drippings from pan.
Add onions and garlic to pan. Stir often until onion is lightly browned, about 5 minutes. Add green pepper, enchilada sauce, tomato paste, sugar, mustard, beans, and bacon. Stir often until boiling, then reduce heat and simmer, stirring occasionally, until flavors are blended, 5 to 10 minutes. Pour into a serving bowl.