1. Preheat grill to high heat.
2. Lightly coat bell pepper pieces with cooking spray. Place bell pepper pieces, skin side down, on grill rack; grill 12 minutes or until skins are blackened. Place bell pepper pieces in a zip-top plastic bag; seal. Let stand 15 minutes; peel and chop bell peppers. Discard skins. Sprinkle with 1/2 teaspoon salt and 1/4 teaspoon freshly ground black pepper. Place bell peppers in a large bowl.
3. Rinse and drain lentils; place in a large saucepan. Cover with water to 3 inches above lentils; add onion and bay leaf to pan. Bring to a boil. Cover, reduce heat, and simmer 20 minutes or until lentils are just tender. Drain lentils. Discard onion halves and bay leaf. Add lentils to bell peppers. Add remaining 5/8 teaspoon salt, remaining 1/4 teaspoon black pepper, tomato, and remaining ingredients to lentil mixture; stir well.