Combine first 8 ingredients, stirring well; place mixture in a large zip-top plastic bag. Cut lamb crosswise into 8 (1/4-inch-thick) slices. Place each slice between 2 sheets of heavy-duty plastic wrap; pound each piece to 1/8-inch thickness using a meat mallet or rolling pin. Add lamb to bag; seal and marinate in refrigerator for 8 hours or overnight, turning bag occasionally. Remove lamb from bag; discard marinade.
Sprinkle lamb evenly with salt. Place lamb on grill rack coated with cooking spray, and grill 1 minute on each side or until lamb is desired degree of doneness.
Cut baguette in half horizontally. Coat cut sides of bread with cooking spray. Place bread, cut sides down, on grill rack, and grill 2 minutes or until golden. Cut bread into 16 slices. Serve lamb with grilled bread and bell peppers.