Clean, wash and cut the lettuce into strips. Wash and clean the peppers, remove the core and cut into thin strips. Peel and quarter the apples, remove the core and also cut into thin strips. Peel and fillet the oranges and grapefruit. Cut the tomatoes into narrow wedges. Put all ingredients in a bowl and mix gently. Mix the ingredients for the marinade in a small bowl and pour over the salad, folding in slightly. Let the salad steep for about 10 minutes before serving.