Soak rolls in cold water. Peel and chop the onion. Knead minced meat, squeezed out roll, onion and egg. Season with salt, pepper and sweet paprika. Form approx. 50 walnut-sized meatballs from the minced meat mixture
Heat the oil in a large frying pan. Fry the meatballs for 2-3 minutes on each side in portions. Take them out and let them cool down
Clean and wash the rocket or lettuce. Wash and slice the tomatoes. Cut the meatballs in half horizontally and spread the halves with mustard cream. Cover the lower halves with rocket and tomato, place the upper halves on top