In a small bowl, mix together cumin, paprika, garlic powder, oregano, salt, onion powder, cayenne pepper, and black pepper. Set aside.

Heat a drizzle of olive oil in a large skillet over medium heat. Add the chopped onion and red bell pepper, sautéing until softened and lightly browned. Add the ground beef and cook, breaking it up as it browns.

Once the beef is fully browned, sprinkle the spice blend over it and stir to combine. Add the tomato paste and cook for another 2 minutes.

Pour in the water or beef broth and stir. Add cornstarch and mix well. Stir in the drained black beans and simmer until the mixture thickens slightly. The filling should be moist but without excess liquid. Remove from heat and let it cool slightly.

Wipe the skillet clean and lightly spray with oil. Place a tortilla in the pan with the heat off. Sprinkle 1/4 cup of cheddar cheese on one half, followed by about 1/2 cup of the beef mixture, a few jalapeño slices (if using), and then 1/4 cup Monterey Jack cheese. Fold the tortilla over.

Turn the heat to medium and cook the quesadilla for a few minutes on each side until golden and crisp. The cheese should be melted and the tortilla lightly browned.

Repeat the process with the remaining tortillas and filling.

Slice and serve hot.