Onions peel, halve and cut into strips. Drain mozzarella, cut into slices. Clean and wash the tomatoes, also cut into slices. Wash thyme and, except for a twig, pluck off leaves and chop. Heat the oil. Fry the onions and minced meat for 5 minutes, turning them over. Season with salt and pepper.
Stir in tomato paste. Press the dough flat on a floured baking tray in portions (8 pieces). Spread the mixture, tomatoes and mozzarella on top. Season with thyme. Bake in the preheated oven (electric cooker: 200 °C/ gas: level 3) for 15-20 minutes. Arrange rolls garnished with thyme twig on a plate