• Wash hands for 20 seconds before beginning with recipe.
• Press the Saute button on the Instant Pot until Custom appears. Press the center knob to choose LE2 or LE3 for 10 minutes. Heat the oil and cook the onion until it loses color.
• Add the carrot and celery to the onion and cook until their color brightens.
• Add the sliced mushrooms and cook until they soften and begin to lose water.
• Add the garlic, salt and pepper and Parmesan rinds. Stir to combine and cook until the garlic is fragrant (30 to 60 seconds).
• Add the barley and stir and then add the tomatoes and broth. Stir to combine.
• Place the lid securely on the pot and check to be sure the vent is closed. Choose Pressure Cook on high for 20 minutes. At the end of the cook time, keep the vent sealed and release naturally for 10 minutes.

  Then, open the vent to release any remaining pressure.
• Serve the soup with a drizzle of olive oil on top!

Stove-top instructions

• Heat olive oil in a Dutch oven and add the onion. Cook until translucent and then add the carrot and celery and cook until brightly colored.
• Add the mushrooms and cook until they soften and start to lose water.
• Add the Parmesan rinds, garlic, salt, and pepper, and cook until fragrant (30 to 60 seconds).
• Add the barley and stir to combine and then pour in the tomatoes and broth, stirring. Bring all to a boil and then lower heat to a simmer. Partially cover and cook until the barley is soft, 40 to 50 minutes.