Bring 12 cups water to boil in large pot. Add barley. Cover pot reduce heat to medium. Simmer until barley is tender, about 30 minutes.

Add haricots verts; boil until tender, about 5 minutes. Drain.

Place mixture in large bowl. Mix in tomatoes, olives, onion, 1/3 cup oil, lemon juice, thyme, and lemon peel. (Barley can be made 2 hours ahead. Cover and let stand at room temperature.)
 

Preheat broiler. Whisk 1/2 cup oil and garlic in bowl. Turn fish in oil mixture; divide fish between 2 rimmed baking sheets.

Toss peppers in oil mixture divide between baking sheets. Drizzle remaining oil from bowl over fish and peppers. Sprinkle with salt and pepper.

Place 1 pan in broiler 3 minutes. Turn fish over, broil until fish is opaque in center and peppers begin to blacken, about 2 minutes longer. Repeat with remaining fish and peppers.

Divide barley salad among plates. Top with fish and peppers and drizzle with pan juices. Serve with lemon wedges.