Finely slice onions and sprouts (or use a food processor). Heat oil in a large frying pan on medium heat. Add onions, sprouts, paprika, salt, and pepper. Cover and cook for 10 minutes, stirring occasionally.

Remove the lid and add mushrooms. Fry for 10 minutes more, until mushrooms are soft.

Heat a frying pan on medium heat and add a tortilla. Top with 1/4 of the vegetables and add parmesan and mozzarella. Layer another tortilla on top. Cook several minutes on each side, until nice and toasted. Repeat for remaining quesadillas.

Let cool for 2 minutes before cutting. Serve with sour cream spiked with sriracha.