Wash and clean the mushrooms and tomatoes and cut them into thin slices. Clean, wash and drain the lettuce and cut into strips. Peel onion and cut into thin slices.
Mix vinegar, mustard, salt and pepper and add oil. Mix mushrooms, tomatoes, lettuce, onion, cheese, corn and dressing. Arrange salad on a plate and sprinkle nuts on top. Spread wholemeal taler with margarine and eat with the salad.