Add the remaining 1 teaspoon oil to the pan. Add onion and cook, stirring, until softened, 3 to 4 minutes. Stir in garlic and cook, stirring, until fragrant, 30 seconds. Add orange juice and cook until most of the liquid has evaporated, 30 seconds to 1 minute. Stir in barbecue sauce. Return the pork chops to the pan, turning several times to coat with the sauce.