Season the chicken thighs with salt and pepper. Set your Instant Pot to sauté mode and add the olive oil. Brown for about 3 minutes on each side. Set aside.
Add the chopped onion, bell pepper, and sliced mushrooms to the pot. Sauté for about 4-5 minutes until the vegetables soften, then stir in the minced garlic and cook for another minute.
Pour in the crushed tomatoes, tomato paste, dried oregano, dried basil, and chicken broth. Stir well to combine all ingredients. Return the browned chicken to the pot.