Knead minced meat, breadcrumbs, tomato paste and egg. Season with salt and pepper. Shape the minced meat mixture into 4 flat meatballs with wet hands. Spread out the chips on a baking tray and bake in a preheated oven (electric cooker: 225 °C/ convection oven: 200 °C/ gas: level 4) for about 20 minutes until golden brown. Turn after 15 minutes. In the meantime, heat clarified butter in a pan and fry the meatballs on each side for about 5 minutes until golden brown. Then place a slice of pineapple and a slice of cheese on each of the meatballs, cover them and let them melt at low heat for 4-5 minutes.
In the meantime clean, wash and spin-dry the salad. Wash the cucumber and cut into slices. Wash tomatoes, dab dry and cut into slices. Cut open bread roll and spread the lower halves thinly with mayonnaise. Cover with lettuce, cucumber, meatballs and tomatoes. Place the upper halves of the roll on top and serve with chips. Serve with ketchup and mayonnaise