Heat the oven to 200°C (180°C in a fan oven), 400°F, gas 6 and soften the roll in cold water.
Fry the onion in hot butter. Remove from the heat and add the meat, wrung-out roll, parsley, pepper (keep 1 tbsp back), eggs, mustard, salt and ground black pepper.
With damp hands shape the mixture into twelve small balls and place them in paper cases. Place in the oven and cook for 25-30 minutes. Garnish with the remaining pepper and the parsley.
Make cuts in the potatoes but make sure they remain in one piece. Brush the potatoes with oil and place them in paper cases. Season with salt, ground black pepper and caraway and sprinkle the cheese on top. Roast for approx. 40 minutes. Serve garnished with cherry tomatoes and rocket.