Soak rolls in cold water. Peel and finely chop the onion. Knead with minced meat, squeezed out roll and egg. Finely dice the gouda. Clean, wash and cut leek into fine rings.
Knead cheese and leek into the minced dough. Season minced dough with salt, pepper and paprika. Form 12 meatballs. Heat the oil in portions in a pan. Fry the meatballs in it in 2 portions all around for approx. 8 minutes until crispy