Place the tomatoes, mushrooms, zucchini, onion and peppers in a sealed plastic bag. Add the Italian dressing and shake to coat the vegetables evenly. Marinate the vegetables for at least 10 minutes.
In a saucepan over high heat, combine the rice and water. Bring to a boil. Reduce heat to low, cover and simmer until the water is absorbed and the rice is tender, about 30 minutes. Transfer to a small bowl to keep warm.
Prepare a hot fire in a charcoal grill or heat a gas grill or broiler. Away from the heat source, lightly coat the grill rack or broiler pan with cooking spray. Position the cooking rack 4 to 6 inches from the heat source.
Thread 2 tomatoes, 2 mushrooms, 2 zucchini slices, 1 onion wedge, and 1 green and red pepper slice onto each skewer. Place the kebabs on the grill rack or broiler pan. Baste with leftover marinade. Grill or broil the kebabs, turning as needed, until the vegetables are tender, about 5 to 8 minutes.
Divide the rice onto 2 plates. Top with 2 kebabs and serve immediately.