Wash and dry the spinach and lettuce.
Cut the red onion into half rings, add the lemon juice from half a lemon and leave to marinate for 15 minutes.
Cut the Apple, remove the core and cut into slices, but not too thinly.
Heat a frying pan and fry the slices in vegetable oil. A little pepper and salt.
Mix the spinach, lettuce leaves (tear with your hands) and pickled red onions.
Cut the mozzarella into plates (or if desired) and add it to the salad bowl along with the Apple slices.
For the dressing, mix 2 tbsp of Apple cider vinegar and vegetable oil (or to taste), pour over the salad and mix. If necessary, add salt and pepper to taste.