Bring water to boil in a medium saucepan; stir in couscous and salt. Reduce heat and simmer 8 to 10 minutes or until al dente; set aside. Preheat a charcoal or gas grill for direct cooking over medium heat (350°).

Place yellow and red peppers and zucchini in a medium bowl. Drizzle with 2 tablespoons olive oil; toss to coat. Sprinkle with 2 teaspoons za'atar seasoning; toss to combine.

Spray a grill basket with nonstick spray. Spread vegetable mixture in basket. Grill 6 to 7 minutes or until crisp-tender, stirring frequently. Remove from grill.

Pat scallops dry with paper towels. Place in medium bowl. Add remaining 1 tablespoon olive oil, 1 tablespoon lemon juice, and remaining 1 teaspoon za'atar seasoning. Toss to coat evenly.

Grill scallops 6 to 8 minutes or until scallops reach 145°, turning halfway through.

Place cooked couscous, 2 tablespoons parsley, 2 sliced green onions, and remaining 2 tablespoons lemon juice in another medium bowl; toss until combined. Spoon couscous mixture into 4 serving bowls. Top with cooked scallops, grilled vegetables, and garbanzo beans. Garnish with additional parsley and green onions; serve with lemon wedges, if desired.