Preheat oven to 425ºF. Brush a large rimmed baking sheet with 1 Tbsp. of the olive oil.
Heat remaining 1 Tbsp. olive oil in a large skillet over medium. Add bell pepper and onion; cook 5 to 6 minutes, until soft. Add garlic, adobo sauce, chili powder, and cumin; cook 2 more minutes, until aromatic.
Add black beans and broth. Use a potato masher or the back of wooden spoon to partially mash about half of the black beans. Simmer for 2 to 3 minutes, until the mixture thickens. Stir in cilantro, lime juice, and salt.
Place tortillas on a plate and cover with a damp paper towel. Microwave for 30 seconds, until tortillas are warm and pliable. Arrange tortillas on prepared baking sheet. Sprinkle half of the tortilla with a little cheese, followed by a spoonful of the black bean mixture. Top with another light sprinkle of cheese, and fold over tortilla; press to adhere. Repeat with remaining tortillas.
Bake for 10 to 12 minutes, until the cheese is melty and tortillas are slightly crisp. Let stand for 2 minutes before transferring tacos to a platter and garnishing with toppings of choice.
