Heat the oil in a medium frying pan over a medium heat and add the red onion. Cook for 5 minutes or until slightly softened, then add the beans, red pepper, tomatoes, chillies, garlic, cumin, tomato puree and smoked paprika. Add a splash of water and season, then cook for 5 minutes until the vegetables are slightly softened. Remove from the heat and stir through the coriander and sweet pickle.
Place a wide frying pan over a medium heat. Add one tortilla to the pan, then top with half the black bean mixture. Spread this evenly over the tortilla and top with half the cheese and half the sliced spring onions. Top with another tortilla wrap and cook for 4-5 minutes, until the bottom is browned, then carefully turn over and cook on the other side for a further 4-5 minutes, until the cheese has melted and the base of the quesadilla is brown. Remove from the pan and keep warm, then repeat with the remaining ingredients and serve.