Bring 600 ml salted water to the boil, add rice and allow to swell for about 20 minutes. In the meantime remove the outer wilted leaves from the Chinese cabbage. Loosen about 16 leaves and cut the stalk flat.
Blanch Chinese cabbage leaves in boiling salted water for about 1/2 minutes. Remove, rinse in cold water and drain. Take rice out of the pot, let it cool down and mix about 200 g with the mince.
Put in a cool place for about 2 hours. Whip the cream until stiff. Gradually add the sugar. Remove the cake from the edge of the springform pan. Dust the surface evenly with cocoa. Pour the cream into a piping bag with a star-shaped spout and decorate the cake with cream tuffs.
Heat 1 tablespoon of oil in a frying pan and fry the rolls in it for about 15 minutes over medium heat until they are round. In the meantime peel and finely dice the onion. Heat the rest of the oil in a pan and sauté the onion in it.
Dust with paprika, stir in tomato paste and add stock. Let simmer for about 10 minutes. Put the rest of the rice in a pot with 2-3 tablespoons of water and warm it up on a low heat with the lid covered.
Stir starch with 1 tablespoon of water until smooth and thicken the stock. Arrange the Chinese cabbage rolls with sauce on a plate and garnish with the remaining marjoram. Serve remaining rice separately.