See link in post on how to cook Barley.
Preheat oven to 400.
In a bowl toss together onion, mushroom, thyme, garlic, cover with a high heat oil (grape seed etc). Put the contents on a baking sheet. Sprinkle with salt and pepper. Roast for Approximately- 30 minutes, until the vegetables are brown and tender.
Toss barley, cilantro, parsley, lemon juice, Parmesan, and 2 Tbsp. in a large bowl to combine; season with salt and pepper. Add roasted vegetables; toss again to combine.
Just before serving, more shaved Parmesan.