Wash the meat, dab dry, cut in half diagonally and cut a pocket in each half. Season with pepper. Cut ham and cheese slices in half. Fill each pocket with 1/2 slice of ham and cheese.
Season meat with salt. Whisk eggs on a deep plate. Turn escalopes one after the other in flour, egg and breadcrumbs. Peel onions and cut into cubes. Wash and halve the tomatoes. Clean, wash and drain the salad.
Heat 1 tablespoon of oil in a large, coated frying pan. Reduce heat and deglaze oil with butter. Fry the escalopes for 4-5 minutes on each side until golden brown. Season the vinegar with salt, pepper and sugar and fold in 4 tablespoons of oil.
Arrange lettuce, onions and tomatoes in small bowls, drizzle with dressing. Drain cutlets on kitchen paper. Arrange cutlets on preheated plates, garnish with basil and halved lemon slice.
Baguette tastes good with it.