Peel the onions and cut off one lid each. If necessary, hollow out the onions with a ball cutter. Finely dice half of the onion inside. Peel the garlic and press it through a garlic press.
Wash the tomatoes and cut them into pieces. Heat 2 tablespoons of oil in a pan. Sauté onion cubes and garlic in it. Add the couscous. Deglaze with 1/2 litre stock, add tomatoes and simmer for 2-3 minutes while stirring.
Season with salt, pepper and cumin. Fold in raisins and pistachios. Put onions on a fat pan. Fill with the prepared couscous. Sprinkle with parmesan. Spread the rest of the onion interior around the stuffed onions.
Pour on 1/4 litre of broth. Bake in the preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: level 2) for 30-40 minutes. Wash the meat and pat dry. Heat 2 tablespoons of oil. Fry meat for 2-3 minutes on each side.
Season with salt and pepper. Arrange everything and serve with mint yoghurt.