Pressed barley is called oshimugi in Japanese. It’s just like rolled oats. By flattening the barley, it can be cooked quicker.
Until around the beginning of the 20th century, many Japanese ate rice only on special occasions. It was barley or millet that regular people ate everyday. As they even didn’t have pressed barley, it used to take long to cook barley. Pressed barley significantly reduced the cooking time.
People recently use pressed barley for many different recipes, including soup, salad, and stew, as it is rich in fiber, protein. Some health conscious people even prefer it over rice. Traditionally the Japanese cooked barley plain, just like they cooked rice, and ate barley as they ate rice.
Most often, pressed barley is cooked by itself or cooked with rice. The ratio of barley and rice is up to the personal preference. Using a rice cooker, you can cook it as you would cook rice. For mugitoro rice, the rice mixed with pressed barley is usually used.
Unlike rice, oshimugi doesn’t have to be washed. If you cook oshimugi mixed with rice using a rice cooker, just wash rice as you would normally, and add oshimugi before adding water in the rice cooker.
Pressed barley can be found at Japanese or Korean grocery stores.