On a work surface, chop the garlic with the pepper flakes. In a bowl, combine all the ingredients with a whisk. Season with salt and pepper.
Preheat the grill, setting the burners on high. Oil the grate.
Place the vegetables, except for the tomatoes, on a large baking sheet and brush with the oil. Season with salt and pepper. Grill the mushrooms in a grill wok with holes or threaded on wooden skewers. Grill the vegetables until tender. Cut the cooked zucchini into thick slices. Place the grilled vegetables and tomatoes in a large serving platter and drizzle with the dressing.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.