Season the chicken with black pepper and sprinkle with the thyme. Heat the oil in a 6-quart pressure cooker over medium-high heat. Add the chicken and cook for 10 minutes or until the pieces are well browned on both sides. Pour off any fat.
Stir the broth, wine, lemon juice and garlic in a small bowl and pour the mixture over the chicken.
Close the cooker and cook over medium heat for 8 minutes with the regulator set to slow steam escape. Remove the cooker from the heat and quick release the pressure.
Carefully open the cooker lid and remove the chicken from the cooker. Thicken the sauce, if desired. Serve the sauce with the chicken. Garnish with lemon slices, if desired.