Heat the oil in a large saucepan, add the onion and cook for 3 minutes until starting to soften. Add the garlic and pepper and cook for 3 minutes more. Stir in the cumin and oregano, then add the tomatoes, followed by the beans. Leave to simmer for 10 minutes. Stir in the chocolate until melted and season to taste.
Toss all the salsa ingredients together. Spoon the chilli into serving bowls and top with the salsa.