Chop and sauté onion, leek and carrots in the butter and oil (for 3-5 minutes), followed by chopped celery, bay leaf and peppers.
Combine flour with the cacao powder and spices and add to the sautéed vegetables, mixing well and stirring for about 2 minutes.
Pour in the broth and if wanted the bean. Over medium-high heat bring the mixture to a boil, while stirring continuously. Once it’s boiling, reduce the heat and let it simmer for about 10 minutes.
Add lime juice and cilantro (or parsley) and taste. Keep some herb leaves for garnish.