Mash the kidney beans roughly with a fork in a bowl. Leave some beans whole for texture.
Mix in the cumin, chilli flakes, oregano, salt and chopped red onion.
Lay out a tortilla and sprinkle a quarter of the grated cheese over one half.
Spread a quarter of the bean mixture over the cheese, then top with more cheese.
Fold the tortilla in half and press down gently.
Heat a tablespoon of oil in a frying pan over medium heat. Cook the quesadilla for 2 to 3 minutes on each side until golden and crispy.
Cut into wedges and serve hot.