Clean the mushrooms (wash as desired) and cut in half. Peel and finely chop the onion. Peel garlic and chop very finely. Clean, wash and halve the tomatoes. Heat the oil in a coated pan, fry the mushrooms in it while turning.
Shortly before the end of the frying time, add onion, thyme and garlic. Season with salt and pepper. Mix in the tomatoes. Stir in crème légère. Halve the rolls and place them on a baking tray lined with baking paper with the cut edge facing upwards.
Spread the mushroom vegetables evenly on the halves of the rolls, sprinkle with cheese and bake in a preheated oven (electric range: 200 °C/ gas: level 3/ convection oven: 175 °C) for 10-12 minutes. Sprinkle with pepper and serve on lettuce leaves garnished with thyme, tomato consommé and oregano leaves.