Make the spice mix: In a small bowl, combine the onion powder, dried oregano, salt, cumin powder, paprika, black pepper, and cayenne pepper (if using).

Make the beef filling: Heat the olive oil in a skillet over high heat. Add the onion and cook until softened, about 5 minutes. Add the ground beef and cook until browned, breaking it up as it cooks. Add the capsicum, tomato paste, water, and spice mix. Cook for 2 minutes, or until the sauce has thickened. Transfer to a bowl and let cool.

Make the chicken filling: Drizzle the chicken with 1 tablespoon of olive oil and toss to coat. Sprinkle with the spice mix and toss to coat. Heat 1 tablespoon of olive oil in a large skillet over high heat. Add the onion and garlic and cook until softened, about 5 minutes. Add the capsicum and cook for 1 minute. Transfer to a bowl and let cool.

Make the vegetable filling: Heat the olive oil in a skillet over high heat. Add the onion and garlic and cook until softened, about 5 minutes. Add the capsicum, beans, corn, tomato paste, water, and spice mix. Cook for 2 minutes, or until the sauce has thickened. Transfer to a bowl and let cool.

Assemble the quesadillas: Place a tortilla on a work surface. Sprinkle one side with cheese, top with your choice of filling, and sprinkle with corn and coriander. Fold the tortilla in half.

Cook the quesadillas: Preheat a nonstick skillet over medium-low heat (no oil, if pan is not nonstick use 2 tsp oil). Place a quesadilla in the skillet, press down lightly, and cover with a lid. Cook for 3 minutes, or until the underside is golden brown and crispy. Carefully flip the quesadilla over and cook for 3 minutes more, or until the other side is golden brown and crispy.

Serve immediately with your favorite dipping sauce.