Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add 1 diced red onion and 1 chopped bell pepper, sauté for about 5 minutes. Add 2 minced garlic cloves, 1 teaspoon ground cumin, 1 teaspoon chili powder, salt, and pepper to taste, cooking for an additional minute.

In a mixing bowl, combine the sautéed vegetable mixture with one 15-ounce can of rinsed and drained black beans. Lightly mash the beans, then stir in half of the shredded cheese.

Heat a non-stick skillet over medium heat with olive oil. Place a large flour tortilla in the skillet, spread some black bean filling on one half, add more shredded cheese, and fold the tortilla.

Cook the folded quesadilla for 3-4 minutes on each side until golden-brown and crispy. Repeat with remaining tortillas and filling.

Slice the quesadillas into wedges, garnish with chopped cilantro, and serve with sour cream and salsa.