Heat a non-stick frying pan over high heat. Add beef and cook, stirring with a wooden spoon to break up any lumps, for 5 minutes or until the mince changes colour. Add paprika and cook, stirring, for 1 minute or until combined. Add tomatoes and cook, stirring occasionally, for 5 minutes or until combined and thickened slightly. Set aside for 5 minutes to cool.
Preheat oven to 120°C. Heat 1 teaspoon of oil in a frying pan over medium heat. Add a tortilla and spoon over one-quarter of the mince mixture. Sprinkle with one-quarter of the cheese and top with a tortilla. Use a spatula to press tortilla down. Cook for 1 minute or until golden. Turn quesadilla over and cook for a further 1 minute or until golden. Transfer to an oven tray and place in oven to keep warm. Repeat with remaining oil, tortillas, mince and cheese.
Meanwhile, combine the avocado and coriander leaves in a small bowl. Cut each quesadilla into wedges. Place on serving plates, dollop with sour cream and top with avocado mixture. Serve immediately.