All ingredients ready? Let's begin!
In a large skillet (preferably cast iron) over medium heat, warm 2 teaspoons of the oil. Add the onion and sauté until soft, approximately 3 minutes.
Add the bell pepper and jalapeno pepper to the pan and continue to cook for about 5 minutes.
Stir in the chili powder, cumin, and salt. Add the black beans and stir to combine well. Stir in 1/2 of the cheese and turn off the heat while the cheese melts.
In another cast-iron skillet over medium heat, add 1/2 teaspoon of the remaining oil. Then, warm a tortilla until it is pliable, approximately 1 minute.
Spoon about 1/3 cup of the bean mixture on 1/2 of the tortilla. Top with some shredded lettuce and a little more cheese. Fold the empty half of the tortilla over the filled half. Cook the quesadilla until it is golden on the bottom, about 2 minutes. Flip the quesadilla over and cook until the other side is golden. The tortillas should be golden brown and a little crisp.
Transfer the quesadilla to a cutting board and tent loosely with foil to keep warm. Alternatively, place the tortilla on a sheet pan inside a low oven (200°F) to keep it warm. Repeat this process until all of the quesadillas are cooked.
Using a sharp chef’s knife, slice the quesadillas into wedges and serve with vegan sour cream or guacamole.
Serve while warm.