Mustard dressing: in a container, mix mustard, vinegar, garlic, salt, pepper and olive oil. Keep aside. In another container, mix Cherry tomatoes with olive oil, salt and pepper. Spread on the baking tray covered with a baking sheet. Let roast for 7 to 10 minutes. Keep aside.
In a container, mix fennel and chicories with the lemon juince. Spread fennel, chicories and tomatoes on the plates. Coat with mustard dressing. Decorate with Gruyère AOP strips and cress.