Place shrimp, scallops and mushrooms in bowl. Combine soy sauce, rice wine vinegar, sesame oil, ginger and red pepper sauce. Pour over seafood and toss well. Cover and refrigerate while cooking barley.
To cook barley, spray a large deep skillet with non-stick cooking spray. Heat vegetable oil in skillet over medium heat. Add onion, green pepper, carrot and garlic; sauté until onion is translucent.
Add barley and clam nectar. Bring to boil. Reduce heat and simmer, covered, for 35 minutes, stirring occasionally.
Stir in broccoli and seafood with marinade. Cover and cook 15 minutes longer or until barley is tender and seafood is cooked. Sprinkle with toasted sesame seeds and serve.