Add olive oil to the InstantPot and set to ‘Saute”. Season the chicken with ¼ teaspoon salt and ¼ teaspoon black pepper. Once the oil is shimmering, add chicken and cook for 3 to 4 minutes per side, or until golden brown. Remove chicken from the pot and set aside.
Add the onion, celery and mushrooms and cook, stirring often, for 5 to 7 minutes, or until softened. Add the oregano and garlic and cook for 1 minute, or until fragrant. Add the rice and chicken stock and stir to combine.
Return the seared chicken and remaining salt and pepper to the InstantPot and place the lid on top with the vent set to the ‘seal’ position. Cook at manual high pressure for 10 minutes, then let the pressure release naturally for 10 minutes. Release remaining pressure manually. When you are able to open the lid, remove the chicken and shred into bite-sized pieces.
Stir the Greek yogurt, parsley, Parmesan and shredded chicken into the contents of the InstantPot and serve warm.
Notes
Makes about 6 cups.Storage:Place leftovers in an airtight container and store in the refrigerator. To reheat, place leftovers in a small or medium saucepan over medium-low heat and heat gently, stirring often, until hot. If needed, add a splash of water or broth. Instant Pot chicken and rice will keep for up to four days in the fridge.