Cut the onion into wedges and sweat in the oil until translucent. Stir in the minced meat, season with salt, pepper and deglaze with the red wine. Add the tomatoes and oregano, stir in the rice, add the stock (ratio 1: 2) and bring to the boil.
Cover the ragout and let it stew for approx. 20-25 minutes. The ragout should have a light and juicy consistency. Before serving, stir in the butter and sprinkle with grated cheese.