Cut flat bread lengthwise into thumb-thick strips. Wash thyme, dab dry, remove coarse stalks. Chop thyme. Form a larger piece of aluminium foil into a roll and place it on a baking tray lined with baking paper.
Lean one end of the flatbread strips against the roll, sprinkle with thyme and parmesan. Bake in the preheated oven (electric range: 200 °C/ convection oven: 175 °C/ gas: level 3) for 5-10 minutes until golden brown.
In the meantime peel the apple, remove the core and dice finely. Sprinkle with lemon juice immediately. Mix wasabi, 6 tablespoons of water and 1 tablespoon of crème fraîche. Mix 2 tablespoons of crème fraîche and milk.
Take the chips out of the oven and let them cool down. Wash fish thoroughly, dab dry and cut into fine cubes. Peel and finely chop the shallots. Mix fish, shallots, oil and apples in a bowl, season with salt and pepper.
Arrange wasabi sauce as a mirror on plates. Arrange the tartar in portions on the plates using a ring (approx. 8 cm Ø). Pour crème fraîche in patches on the wasabi sauce and draw stars with a knife.
Put chips on the tartar and serve.