Halve the peppers, remove the seeds and press flat. Place on a grid covered with aluminium foil. Roast under the grill until the skin turns brown and blisters. Remove skin immediately.
Cut the halves in half. Cut aubergines into 1 cm thick slices and season with salt. Leave to stand for about 10 minutes, then dab dry. Peel garlic and onion. Cut garlic into sticks, onion into slices.
Heat half of the olive oil in a pan. Fry the aubergine slices and onion in it in portions for about 3 minutes. Add some garlic at the last minute. Wash and clean the mushrooms.
Steam in the remaining oil for about 8 minutes. Drain the beans. For the marinade, chop 1 bay leaf and the remaining herbs finely. Mix with vinegar, salt and pepper. Finally, beat the oil into it.
Arrange vegetables separately. Cut the drained tuna into pieces and place on the beans. Pour the marinade over the vegetables. Cover and leave to marinate for about 2-3 hours. Finally garnish mushrooms with lemon wedges and remaining bay leaves.