Water 6 wooden skewers for 10-15 minutes. Cook the potatoes with salt and bay leaf for about 20 minutes. For the mayonnaise, mix the egg yolk and mustard in a high container with the whisk of the hand mixer. First fold in the oil drop by drop until the egg yolk begins to bind, then let the remaining oil run in. Season mayonnaise with orange juice, salt and pepper
Drain the potatoes, quench them, let them cool down. In the meantime wash and slice the zucchini. Wash tomatoes and dab dry. Put potatoes, zucchini and tomatoes alternately on skewers
Grill the skewers on the preheated grill for approx. 8 minutes while turning. Arrange and serve with orange mayonnaise