Wash the thyme, shake dry and pluck the leaves from the stalks. Put some leaves aside for garnishing, chop the rest finely. Mix yoghurt, crème fraîche, milk and lemon juice. Stir in thyme and half of the lemon peel. Season with salt, pepper and sugar
Peel onion and cut into fine rings. Wash, clean and slice the tomatoes. Wash basil, shake dry and pluck the leaves from the stems. Clean, wash and halve the lettuce, cut out the stalk, cut each half first into 3 strips, then into bite-sized pieces. Wash apples thoroughly, cut out core with an apple corer. Cut apples into thin slices
Mix lettuce, tomatoes, onion, apples and basil. Add yoghurt dressing. Arrange immediately on 4 plates. Garnish with remaining thyme and lemon peel