For the dough, dissolve yeast in 400 ml lukewarm water. Knead flour, sugar, 2 teaspoons salt, butter in pieces and yeast water in a bowl with the dough hooks of the mixer to a smooth dough. Cover and leave to rise in a warm place for about 1 hour.
For the filling, clean, wash and quarter the cabbage and cut it into thin strips from the stalk. Peel carrots and onion. Wash the tomatoes. Finely dice carrots, onion and tomatoes. Heat oil in a pan. Fry the minced meat in it until crumbly. Add cabbage, carrots and onion and fry for about 3 more minutes. Fry the diced tomatoes briefly. Season with salt and pepper.
Knead the yeast dough again briefly, roll out to a thickness of approx. 3 mm on a little flour. Cut out a total of approx. 55 circles (each approx. 10 cm Ø) from the dough.
Place approx. 1 tbsp. chopped filling in the middle of each dough circle. Form dough circles into little boats (see tip) and place them on a greased baking tray (approx. 35 x 40 cm). Whisk egg yolk and milk and brush the edges of the dough with it. Sprinkle cheese on top. Bake in a preheated oven (electric cooker: 200 °C/circulating air: 180 °C/gas: see manufacturer) for approx. 30 minutes. Tomato sauce tastes good with it.
TIP: Press the dough circles together on two opposite sides to create a rim around the filling.