Preheat the oven at 200 degrees Celsius.
Cut the onion in thin slices.
Fry the mince beef and the onion in the frying pan.
Add the taco spices in the frying pan and add two third of the grated cheese and stir together so the cheese melts.
Divide the mince beef mixture on one half of the tortilla breads. Fold them in half, and dived the breads in three .
Place the quesadillas on a baking sheet, and place them in the middle of the oven for ten minutes.
Take out the quesadillas and serve them warm with some guacamole sauce and some vegetables.