Wash the potatoes and cook in boiling water for about 20 minutes. Drain and wrap in aluminium foil. In the meantime wash and dry chicken filet. Peel and halve the onion. Wash and halve the tomato.
Cut zucchini into thick slices. Season meat and vegetables with salt, pepper and thyme. Cook fillet and potatoes on the hot grill for about 15 minutes, remaining ingredients for about 5 minutes. Add the herb quark. Serve garnished with fresh herbs