Clean, wash and cut the leek into rings. Peel onions and cut into thin rings. Cut meatloaf into strips. Heat oil in a pan. Fry the Leberkäse in it while turning, take it out.
Sauté the leek and onions in the frying fat for 4-5 minutes. Season with salt and pepper.
Stir the sour cream and mustard until smooth. Unroll the pizza dough and place it on a baking tray with baking paper. Spread the dough with sour cream.
Spread the meat loaf, leek and onions on the dough. Sprinkle cheese on the pizza. Bake in the preheated oven 2nd shelf from below (electric oven: 225 °C/ convection oven: 200 °C/ gas: see manufacturer) for approx. 20 minutes.
Take the pizza out of the oven and cut it into 6 pieces.