Heat olive oil in a pan and add chopped onions. Cook until translucent.
Add black beans, chipotle peppers, adobo sauce, maple syrup, vegetable broth, tamari, and salt and pepper. Stir. Cook until the liquid is dissolved. Mash the beans slightly if desired.
On lettuce leaves, pile on maple chipotle black beans, sliced avocado, and mango salsa.
Notes
The black bean mixture will last 5 days in an airtight container in the fridge.