Just as cacao adds depth to mole sauce, it works wonders here too, bringing complexity, richness, and a pleasant, subtle bitterness to this comforting soup. A cool garnish of sour cream and mint provides a stunning contrast.
Adding salt to onions as they sauté helps draw out water so onions soften more efficiently.
Per serving:
Place beans in large bowl, cover with water, and let soak for several (6 or more) hours. Drain.
Heat oil in large saucepan over medium heat. Add onion and 1/2 tsp (2 mL) salt to pan and heat until onion is softened and translucent. Place carrots and garlic in pan; heat for 2 minutes. Stir in cacao powder, coriander, cinnamon, red pepper flakes, and remaining 1/4 tsp (1 mL) salt; heat for 30 seconds. Place drained beans, tomatoes, and 4 cups (1 L) water in pan, bring to a rolling boil, reduce heat to low, and simmer, covered, for 45 minutes, or until beans are tender.
Place soup in serving bowls, top with dollops of sour cream, and sprinkle mint overtop.