1. Preheat broiler.
2. To prepare pepper sauce, cut the bell peppers in half lengthwise; discard seeds and membranes. Place bell pepper halves, skin sides up, on a foil-lined baking sheet; flatten with hand. Broil for 12 minutes or until blackened. Place in a paper bag, and fold to close tightly. Let stand for 20 minutes. Peel. Place peppers and the next 8 ingredients (through red pepper) in a blender, and process until smooth.
3. Preheat grill to medium-high heat.
4. To prepare couscous, combine 1 cup water, broth, and bay leaf in a medium saucepan; bring to a boil. Stir in couscous; cover. Remove from heat; let stand 10 minutes. Fluff with a fork; discard bay leaf.
5. Arrange eggplant and the next 3 ingredients (though green onions) on grill rack coated with cooking spray; grill 3 minutes on each side or until vegetables are tender and well marked. Remove from heat; coarsely chop vegetables. Combine 1/2 cup pepper sauce, couscous, and chopped vegetables in a large bowl; toss gently. Keep warm.
6. To prepare skewers, thread beef onto 12 (7-inch) skewers. Lightly coat beef with cooking spray, and sprinkle with black pepper and 1/2 teaspoon salt. Place skewers on grill rack coated with cooking spray; grill 8 minutes or until desired degree of doneness, turning once. Serve with couscous mixture and remaining sauce.