Put rice in well 1⁄4 l boiling salted water. Cover and cook for about 15 minutes. Let dough rest for about 10 minutes at room temperature.
Peel and chop the onion. Clean, wash and halve the mushrooms. Clean, wash and cut cabbage into fine strips. Wash and chop the dill.
Fry the mushrooms and onion in hot oil. Fry the Chinese cabbage for 2-3 minutes. Season everything with salt and pepper. Drain the rice if necessary, stir dill into the vegetables with 2⁄3 Season to taste.
Roll out the dough. Place the rice mixture lengthwise as strips in the middle. Cut the dough diagonally into 2 cm wide strips on both long sides. First fold the ends of the dough, then the strips alternately overlapping over the filling.
Mix the egg yolk and cream. Spread the roll with it. Bake in a hot oven (electric oven: 200 °C/circulating air: 175 °C/gas: level 3) for 40-50 minutes. Mix mayonnaise, sour cream and the rest of the dill, season to taste.