1 tsp vegetable oil
1 diced onion
3 cloves garlic, sliced thin
1 Tbs ground cumin
1/4 tsp cayenne
1 15-oz. can diced tomatoes with green chili, with juice
1 15-oz. can black beans, drained
water or broth to thin
Saute onion and garlic for 5 minutes. Add cumin and cayenne, stir for 1-2 minutes. Add tomato and beans; bring to a strong simmer. Partially puree with a stick blender and season with salt and pepper. Add hot water or broth to thin to desired consistency.
Incredibly simple and very good!
Adapted from the Soup Peddler