You are here: Home » Recipes » Barley and Mushroom Casserole Barley and Mushroom Casserole Recipe by Relish ContributorKitchen Tested Yield 6 to 8 servings Fiber-rich barley is a great alternative to rice. PrintEmail Ingredients 1 tablespoon margarine1/2 pound fresh mushrooms, sliced1 (3 1/2-ounce) package shiitake mushrooms1 cup medium barley pearl1 envelope onion soup mix4 cups water Instructions Preheat oven to 350F. In a small skillet, melt the margarine and saute both kinds of mushrooms until tender, about 5 minutes; set aside. In a 3-quart casserole dish, combine the barley, onion soup mix and water. Stir in the mushroom mixture. Cover and bake for 1 hour to 1 hour 15 minutes or until the barley is done and the liquid absorbed.