Wash mixed grains such as brown rice, barley, oats, and white rice thoroughly.
Soak the washed grains in water for about 30 minutes.
Add an appropriate amount of water to the soaked grains.
Put the grains and water into a rice cooker or a pot and cook the rice.
Let the cooked rice sit for about 10 minutes to finish steaming.
Mix the rice evenly and serve on a plate.