Combine the mince with a grated onion head, 2 eggs, the rice, parsley and black pepper. Form meatballs from the mixture. Put the celery, carrots and the other onion head to boil until soft in 5 2/5 cups (1.3 L) of salted water.
Separately, braise the flour in some of the butter, dilute with the strained broth. Beat 2 eggs with the yoghurt and gradually add them into the sauce.
Let it boil, add the meatballs and pour on the rest of the melted butter (mixed with paprika) on top. Serve the fricassee with lemon slices.