Season the chicken thighs generously with salt and pepper on both sides. If you like, add a light dusting of paprika for color and a hint of smokiness.
Set the Instant Pot to Sauté. Add olive oil and let it shimmer. Sear the chicken thighs in batches until golden brown on both sides, about 2–3 minutes per side. They don’t need to be fully cooked through at this stage; you’re building flavor here.
Remove the seared chicken and add minced garlic to the pot. Sauté for about 30 seconds until fragrant, then add lemon zest and juice, chicken broth, and oregano. Stir to combine, scraping up any browned bits from the bottom.
Return the chicken to the pot. Secure the lid, set the valve to sealing, and cook on High Pressure for 6–8 minutes (adjust time if your chicken is larger).
Natural release for 5 minutes, then quick release the remaining pressure. Open the lid carefully.
Transfer the chicken to a serving platter. Turn the pot to Sauté again if you’d like to simmer the sauce a bit more and reduce. Stir in the butter until glossy, and season to taste with additional salt, pepper, and a pinch of red pepper flakes if you love a little heat.
Spoon the sauce over the chicken, sprinkle with chopped parsley, and serve with a light side such as steamed veggies, rice, or mashed potatoes to soak up the bright, lemony sauce.