|Place barley and broth in a 2 quart saucepan and bring to a boil. Reduce heat, cover and simmer on low for 50 minutes. Remove from heat and allow to "steam" cook another 10 minutes. Spoon out into a large bowl to cool.
Meanwhile, place asparagus and mushrooms on a cookie sheet and spray lightly with olive oil cooking spray. Heat oven to 450 degrees and roast vegetables 10 minutes or until vegetables are tender. Cut asparagus into 1" pieces.
Add roasted vegetables and red onion to barley.
Mix olive oil, vinegar, garlic, salt and pepper together and pour over barley. Add dill and toss all together until well mixed. Serve at room temperature.