In a mixing bowl, combine the mozzarella cheese, feta cheese, spinach, tomato, red onion, and black pepper. Mix well.
Lay one tortilla flat and place one-fourth of the filling mixture on half of the tortilla. Fold it over to cover the filling.
Heat a non-stick skillet over medium heat and add olive oil.
Place the filled tortilla in the skillet and cook for about 3-4 minutes until golden brown.
Flip carefully and cook for another 3-4 minutes until both sides are crispy.
Remove from heat, slice into wedges, and serve warm.
