Set the Instant Pot to Sauté and add the butter. When the butter melts, add the chopped onion, sliced red and green bell peppers, and minced garlic; sauté until softened, about 3–4 minutes.
Turn off Sauté. Add the chicken pieces into the pot, then pour in the soy sauce and rice vinegar. Add the bay leaves, kosher salt, and black pepper, stirring briefly to combine.
Close the lid and set the valve to sealing. Cook on High pressure for 15 minutes.
When the cook time ends, let the pressure sit for 5 minutes, then carefully quick-release any remaining pressure and open the lid.
Select Sauté again. Stir and turn the chicken pieces so they simmer evenly in the sauce, and cook for about 5–8 minutes, stirring once or twice to prevent sticking, until the sauce is slightly reduced. Remove and discard the bay leaves.
Serve the chicken and sauce over rice.