1. In a large saucepan or Dutch oven, saute ground beef. Remove beef. Add onions and garlic, saute in beef fat. Add all spices and tomato paste, cook 5 minutes.
2. Add tomato puree, chocolate, water, and vinegar and bring to a boil.
3. Reduce heat and simmer 10 minutes. Add beef, heat through, and season.
4. Serve with fresh cilantro and lime wedges.