Warm the milk until lukewarm, then crumble the yeast into it with your fingertips. Add 1 cup flour and mix all into a smooth dough. Cover and let stand in a warm area to rise. Next, add the butter, egg yolks, salt and the rest of the flour and stir well. Knead into a rather tight and elastic dough.If necessary, add water or flour. Cover with a towel and again set in a warm place to rise a second time. Then knead once more to knock down the dough. Break into small pieces. During the rising of the dough, cook the ground beef. Mix it with 2 tablespoons of butter, a finely chopped onion, chopped parsley and a small quantity of tomato. Cook well, adding 4 or 5 tablespoons of grated cheese just before it is finished. Take a small piece of dough and roll it flat, on a floured board with a rolling pin. Lay one spoonful of cooked ground meat in the center of the dough. Fold the dough in half to form a half-moon shape and enclose the filling. Shape it a little in the palm of your hand to make a more oval shape. Smear with egg white. Place on a greased baking tin and set aside in a warm place to rise. Then deep fry the turnover in oil until each turns a golden brown. Take them from the oil with a perforated spoon, lay on paper towels to drain and serve them warm.
Here are some interesting variations to this recipe:
1. Instead of frying the turnovers, you can bake them in an oven. In this casse, after wrapping the turnovers, put them in a buttered baking pan to rise. Brush the tops with egg white. Then put them in a moderate oven and bake until brown.
2. The meat filling can be made from lean chicken, ham, fish or hard-boiled eggs, chopped and mixed with bechamel sauce or mashed potatoes.
3. Another variation is sweet Russian turnovers. Add 3 tablespoons of sugar together with the salt to the dough. Fillwith jelly or marmalade and chopped candied fruit. Sprinkle with powdered sugar and serve.