Clean and wash the cabbage and cook in boiling salted water for about 5 minutes. Dissolve 2 cabbage leaves. Use the rest of the cabbage for other purposes. Peel onion and cut into fine cubes. Knead minced meat, onion, egg, breadcrumbs and mustard.
Season with salt and pepper. Shape the mince into 2 flat meatballs. Place 1 meatball on each cabbage leaf. Whip the cabbage and roll up. Tie together with kitchen string. Peel, wash and halve the potatoes and cook in boiling salted water for about 20 minutes.
Heat the oil. Fry the roulades in it for about 4 minutes, turning them over. Pour on 50 ml stock and cook for another 10 minutes in the closed pan. Melt the fat in a saucepan. Stir in flour and curry and sauté briefly.
Add 100 ml stock and milk while stirring. Bring to the boil, boil for 3-5 minutes and season with salt and pepper. Wash parsley, shake dry, pluck leaves from stalks and chop except for a little bit for garnishing.
Arrange roulades, sauce and potatoes. Sprinkle with curry and parsley and garnish with parsley.