Instant Pot Mushroom Barley Soup

a bowl of mushroom and pearl barley soup

5 from 5 reviews

Instant Pot Mushroom Barley Soup is incredibly flavorful. The secret ingredient is white miso paste, which adds rich flavor.  This barley soup is vegan and easy-to-make in your Instant Pot. 

Total Instant Pot Cooking Time: 15 minutes to reach pressure + 15 minute cooking time + 10 minute quick release


Units Scale
  • 1/4 cup olive oil
  • 1/2 cup finely chopped onion
  • 1/4 cup finely chopped celery
  • 8 to 12 ounces mushrooms*, roughly chopped into small pieces
  • 1 tablespoon soy sauce
  • 3 cups water
  • 3 cups vegetable broth
  • 1/2 cup uncooked pearl barley
  • 2 to 3 tablespoons white miso

*You can use one type of mushroom or a mix of your favorite types. I use a mix of button/cremini mushrooms and shiitake when I make this soup. 


  1. Use the saute setting on the Instant Pot to warm the olive oil. I like to use the “normal” heat level  because the onion is less likely to burn and stick. To adjust the saute heat level, press “Saute” and then “Adjust” to toggle between “less” “normal” and “more.”
  2. Add the onion and celery. Saute until soft, about 5 minutes. Keep an eye on the onion so it doesn’t burn or stick to the pot. 
  3. Add half of the mushrooms and cook for about 1 minute, stirring frequently, until the mushrooms have cooked down and decreased in size. 
  4. Add the remaining mushrooms and saute several more minutes, stirring frequently, until the mushrooms are very soft. 
  5. Drizzle the soy sauce over the mushrooms and mix well.
  6. Add water, broth and pearl barley.
  7. Secure the lid and cook the soup for 15 minutes on high pressure.
  8. When the cooking time is complete, wait 10 minutes then do a quick release of steam.
  9. In a small bowl, whisk together 2 tablespoons of miso paste with ½ cup of the hot soup broth until very smooth.
  10. Slowly pour the miso into the pot of soup, stirring or whisking as you pour
  11. Taste the soup. I usually add 1 more tablespoon of miso (make sure to whisk it in a small bowl with broth before pouring it into the soup). You can add another tablespoon of miso, or just add salt to taste. 


Right when you open the lid, you might not think that the soup has enough barley. Just wait 10 minutes. As the soup sits, the barley absorbs the broth and plumps up, becoming more noticeable in the soup. 

Stovetop Instructions: You can also cook this soup on the stovetop. Follow the same instructions to saute the veggies in a soup pot, then add water, broth and barley. Simmer gently with a lid, stirring occasionally, for about 30 minutes until the barley is tender. Then follow the instructions above for adding miso.

Storage: This soup will stay fresh for up to 5 days in the refrigerator. You can also freeze the soup if necessary, but the barley gets softer after being frozen and defrosted.

This recipe was tested in a 6-quart Instant Pot

Keywords: instant pot mushroom and barley soup, barley soup, pearl barley, mushroom soup, miso