Heat olive oil in a large skillet over medium heat; cook pork chops in the hot oil until browned, about 5 minutes per side. Transfer browned pork chops to a slow cooker; top pork chops with onion and green peppers.
Whisk tomato sauce, brown sugar, vinegar, Worcestershire sauce, and salt together in a bowl. Pour sauce into slow cooker, gently stirring to coat meat and vegetables.
Cook pork chops on Low until tender, 6 to 8 hours.
Transfer pork chops to a serving platter; tent with aluminum foil to keep warm. Whisk cornstarch into sauce until thickened; spoon sauce and vegetables over pork chops.