Preheat charcoal grill or oven to 425ºF.

Place mushrooms in a medium bowl. Add zucchini, onion, red pepper, couscous and sauce; toss until well coated; set aside.

On a work surface place 4 sheets of heavy duty or doubled aluminum foil, each about 20 inches long. In the center of each piece, place mushroom mixture, dividing equally. Bring long sides of foil together over mixture, allowing space for heat circulation and expansion; crimp together. Fold up short ends; crimp to seal.

Place packets on a rack over preheated grill, about 5 inches from heat source or in the oven. Cook until vegetables are tender and couscous is cooked (on the grill for about 15 minutes, turning once, or in the oven for about 20 minutes). Remove; let stand for 5 minutes. Carefully unfold foil and serve.