In large saucepan over medium heat, heat oil. Add onion and 1/2 tsp salt and heat until onion is softened and translucent. Add carrots and garlic; heat for 2 minutes. Stir in cocoa powder, coriander, cinnamon, red pepper flakes, and remaining 1/4 tsp salt; heat for 30 seconds. Add drained beans, tomatoes, and 4 cups water and bring to a rolling boil. Reduce heat to low and simmer, covered, for 45 minutes, or until beans are tender.