Preheat the oven to 350°F (177°C).
Heat the oil in a large braising pan or oven-safe Dutch oven over medium-high heat. While the pan heats, season the short ribs on all sides with the kosher salt, pepper, and garlic powder. When the oil is shimmering, add the ribs in batches and sear for 2 to 3 minutes per side until deeply browned. Transfer the ribs to a plate and set aside.
1 tbsp (15 ml) neutral oil, 8 (4 lbs / 1.8 kg) bone-in-beef short ribs, 1 tbsp (15 g) kosher salt, 1 tsp (2 g) coarse ground black pepper, 1 tsp (3 g) garlic powder
Reduce the heat to medium and add the butter to the same pan. Once melted, add the onion, carrots, and celery and cook for 5 to 6 minutes, stirring occasionally, until softened and lightly browned. Add the garlic and cook for about 30 seconds, until fragrant. Sprinkle in the flour and add the tomato paste, stirring constantly and pressing the paste into the pan for 2 to 3 minutes.
2 tbsps (28 g) butter, 1 medium yellow onion, 2 medium carrots, 1 medium celery stalk, 2 cloves garlic, 2 tbsps (16 g) all-purpose flour, 3 tbsps (45 g) tomato paste
Slowly pour in the red wine while whisking, scraping up the browned bits from the bottom of the pan. Let the wine simmer for 2 to 3 minutes so the alcohol cooks off and the liquid reduces slightly. Stir in the beef broth, balsamic vinegar, Dijon mustard, salt, and pepper. Add the thyme, oregano, and rosemary sprigs, then return the short ribs to the pan, nestling them into the liquid so they are mostly submerged.
2 cups (480 ml) dry red wine, 2 cups (480 ml) low-sodium beef broth, 1 tbsp (15 ml) balsamic vinegar, 2 tsps (10 g) Dijon mustard, ½ tsp (3 g) kosher salt, ½ tsp (1 g) coarse ground black pepper, 4 sprigs fresh thyme, 4 sprigs fresh oregano, 2 sprigs fresh rosemary
Cover the pan with a tight-fitting lid and transfer to the oven. Cook for 3 to 3½ hours, or until the meat is fork-tender and beginning to pull away from the bone.
Remove the pan from the oven and let the ribs rest, covered, for 20 to 30 minutes before serving. Spoon the sauce over the ribs and serve with mashed potatoes or polenta. Finish with fresh parsley if desired.
mashed potatoes or polenta, fresh parsley