Cut the red onion into very fine slices or strips.
Mix all ingredients for the vinaigrette well or mix in a shaker. Put in the onions and let them steep.
Pluck the parsley from the stalks and roughly chop. Halve the cherry tomatoes. Mix both well in a bowl with the vinaigrette.
Cut the zucchini diagonally into approx. 3 mm thick slices and moisten with a strong dash of olive oil. Grill on the grill for approx. 2 - 3 minutes on each side.
Place the zucchini on a platter, sprinkle with a little coarse salt if you like, and spread the tomato salad on top. If you like, you can add some parmesan cheese to the salad.