To make the bean filling, heat the oil in a skillet over medium-high heat. Add the garlic, chili powder, chipotle, cumin, salt and cayenne; stir, cooking just until fragrant, 30-60 seconds. Add the beans and the water or broth to the pan. Bring the mixture to a boil. Reduce the heat to medium-low and allow the mixture to simmer for 10 minutes. Remove the skillet from the heat, stir in the salsa and mash the mixture with a spoon or fork.