Barley, in a way, is the often overlooked grain. With a satisfying chewiness and a neutral flavor, this is a grain that will take on the flavor of neighboring ingredients just as well as rice. Here, mushrooms and onions lend a savory element to this easy-to-make side dish.
Coat a heavy saucepan with cooking spray and place over medium-high heat. Melt the butter in the pan. Add the onion and cook, stirring occasionally, about 5 minutes. Add the mushrooms and cook until the mushrooms release their moisture, stirring a few times, about 5 minutes.
Add the broth, barley, and salt and bring to a boil. Partially cover the pan and reduce heat to low. Simmer until the barley is tender, stirring occasionally, about 60-75 minutes. Remove from heat and serve.