Add the onion and garlic to the cooker and sauté until the onion just starts to brown, about 5 minutes. Stir in the tomato paste, oregano, thyme and bay leaf. Deglaze with white wine and let it come to a boil. Add the peppers, sliced mushrooms, diced tomatoes, and chicken stock and stir. Return the browned chicken to the pot, submerging it slightly in the vegetables and liquid. Cover and lock the lid in place.