Set the Instant Pot to Sauté mode. Heat the olive oil, then add the onion, carrot and celery. Cook, stirring occasionally, until the vegetables are starting to soften, 3 to 4 minutes.
Add the garlic, thyme, rosemary, salt and pepper. Cook, stirring, for 1 minute.
Add the mushrooms. Cook, stirring occasionally, until the mushrooms are tender, 3 to 4 minutes.
Pour in the uncooked barley and vegetable broth. Stir to combine.
Place the lid on the Instant Pot, close the steam vent and set to HIGH pressure for 20 minutes. It will take about 15 minutes for the Instant Pot to reach pressure.
Once the time expires, use natural release for 10 minutes, then quick release. Carefully open the Instant Pot. Stir in the parsley. Serve.
Notes
For a lower sodium version, use reduced sodium vegetable broth.Please note that I am not a medical or nutritional professional. I provide nutritional information for my recipes as a courtesy to my readers. It is calculated using the built-in recipe card calculator. While I attempt to provide information that is as accurate as possible, you should calculate the nutritional information independently before relying on it.