Fast food "Hedgehogs"

Required: 500 gr. mixed minced meat, 1/2 cup rice, 1 egg + yolk of one egg, 1 onion, 2 cloves of garlic, 1 teaspoon of mustard, 1 large tomato, 1 tbsp. a spoonful of tomato paste, 1 tablespoon of flour, 200 ml of water, 100 ml of cream or sour cream, salt, pepper, spices for minced meat, 50 gr. grated cheese.
Preparation: Boil the rice in salted water until half cooked. Cool, add egg and yolk, stir. Combine rice with minced meat. Season the mass, salt, pepper, add mustard and beat thoroughly. Put the minced meat in the refrigerator for at least an hour. From chilled minced meat, mold about 20 round meatballs. Put the meatballs in a baking dish (greased with vegetable oil) and put in an oven preheated to 190 C for 25 minutes. For the sauce, cut the onion into half rings, chop the garlic. Fry vegetables for 5 minutes in vegetable oil, stirring constantly. Add chopped tomato (it is advisable to remove the skin). Cook for another 5 minutes. Mix the tomato paste with flour, dilute with water and add this mixture to the vegetables. Bring to a boil, pour in cream, salt and season. Remove the meatballs from the oven and pour over the sauce, sprinkle with grated cheese. Return the mold to the oven for about 15 minutes.