6  ea        bone-in beef short ribs (about 3¼ pounds)
¾  tsp      salt, divided (found at The Tea Tree)
½  tsp      ground pepper (found at The Tea Tree)
2   TBSP  Garlic Olive Oil, divided (found at The Tea Tree)
1 med      onion, sliced
2 TBSP    Tomato paste
1 tsp        Fresh thyme (found at The Tea Tree)
1 cup        Apple Balsamic Vinegar (found at The Tea Tree)
½ cup       low-sodium beef broth
2 TBSP     Cornstarch
1/4 cup      water
                 Chopped fresh parsley (optional)

Sprinkle ribs with ½ teaspoon salt and pepper. Heat 1 tablespoon of Garlic Olive Oil in a large skillet over medium-high heat. Add the ribs and cook until browned on all sides, about 5 minutes total.
Transfer to a 6-quart or larger slow cooker.
Add the remaining 1 tablespoon of Garlic Olive Oil and onion to the pan; cook, stirring occasionally, until starting to brown, 3 to 5 minutes. Stir in tomato paste, garlic and thyme; cook, stirring, for 1 minute. Add   Apple Balsamic Vinegar and cook, scraping up any browned bits, until the liquid is mostly reduced, 3 to 5 minutes.
Transfer to the slow cooker and add broth. Cover and cook on High for 4 hours or Low for 8 hours.

Transfer the ribs to a serving platter. Transfer the liquid to a medium saucepan and bring to a boil over high heat. Whisk cornstarch and water in a small bowl and add to the boiling liquid. Cook, whisking, until thickened, about 2 minutes. Stir in the remaining ¼ teaspoon salt. Serve the ribs with the gravy and mashed potatoes sprinkled with parsley, if desired.