Turn the instant pot to saute, add 1 tablespoon of oil, and let heat for a minute or two. While the oil is heating, pat the chicken dry with a paper towel and liberally season with salt and pepper on both sides. Add the chicken thighs to the oil, in a single layer (you may need to work in batches). Cook the chicken until golden on each side, about 3-4 minutes per side. Once golden, remove the chicken and place it on a plate.
If the inner pot is dry, add in the remaining ½ tablespoon of olive oil and add the onions and peppers. Saute for 2-4 minutes, or until onions begin to soften. Once the onion has softened, add in the mushrooms and garlic and saute for another 30-60 seconds.
Add in the wine and deglaze Instant Pot, scraping up any browned bits on the bottom of the pot. Let the wine cook off for 1 to 2 minutes. Turn the Instant Pot OFF by hitting cancel.
To the inner pot, add the chicken stock, oregano, olives, capers, and a pinch of salt and pepper. Stir to combine and then nestle the seared chicken thighs into the sauce. Sprinkle chicken with a bit of salt and pepper. Pour the tomatoes over the chicken thighs and DO NOT STIR!
Close the lid on the pressure cooker, being sure the vent knob is placed towards the sealed position. Cook on high pressure for 7 minutes for boneless chicken thighs and 8 minutes for bone-in chicken thighs.
Once cook time has elapsed, allow pressure to release naturally for at least 10 minutes. After pressure has naturally released, open the Instant Pot and remove the cooked chicken to a new clean plate.
Turn the saute function back on the Instant Pot (hit cancel and then saute). Stir in the balsamic vinegar and then simmer the sauce to thicken, for 3-5 minutes. Taste and adjust the sauce with more salt and black pepper.
Serve chicken with sauce over noodles or rice topped with fresh basil and parmesan if desired.
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Notes
Chicken: I prefer bone-in, skinless chicken thighs for this recipe. If you use boneless, skinless chicken thighs, decrease the cooking time to 7 minutes on high pressure.Wine: I recommend a dry white wine such as a chardonnay or pinot grigio. If you do not drink, feel free to use additional chicken stock in place of the wine.8-Quart Pressure Cooker: Use ¾ cup of chicken stock rather than ½ cup.Storage: Store leftover cooled chicken cacciatore in a sealed container in the refrigerator for up to 3 days. Alternatively, freeze it in a freezer-safe container, leaving ½-inch room for expansion, for 1-2 months.