Preheat your oven to 350°F.
Season the short ribs lightly with salt and pepper. In a heavy, oven-safe pot, heat half a tablespoon of olive oil over medium-high heat until shimmering.
Sear the short ribs on all sides until browned, about 2-3 minutes per side.
Add chopped onion and garlic to the pot and sauté until soft, about 3-4 minutes. Toss in the fresh thyme sprigs.
Pour in beef broth to deglaze the pan, scraping the browned bits off the bottom.
Cover the pot with a lid and transfer it to the preheated oven. Braise the short ribs for about 1.5 to 2 hours until tender.
Meanwhile, prepare the vegetables. Peel and cut the carrot, parsnip, and turnip into uniform chunks. Toss them lightly in a little olive oil, salt, and pepper.
Spread the vegetables on a baking sheet and roast in the oven for about 25-30 minutes until tender and slightly caramelized.
Once both the short ribs and vegetables are cooked, plate a serving portion combining a piece of the ribs with an ample helping of roasted root vegetables.
Drizzle a little of the braising liquid over the meat for extra flavor, then serve immediately.