Heat the grill. Brush salmon with 1 Tbsp of the vinaigrette. Place salmon, zucchini and onion on grill. Grill 3-4 minutes on each side until salmon is done and vegetables are tender, adding tomatoes to the rack after 2 minutes. Cook tomatoes 2 minutes on each side. Cut salmon crosswise into thin slices; coarsely chop zucchini, and cut tomato halves into wedges. Place 1 ½ cups arugula on each of 4 plates. Divide salmon and vegetables evenly among servings. Top with feta and vinaigrette. Serves 4.