Preheat the oven to 325°F (163°C). Heat olive oil in a Dutch oven over medium heat. Pat short ribs dry and season with kosher salt. Sear the ribs until golden-brown crust forms.

Transfer the seared ribs to a plate. Remove excess fat from the pot, retaining about a tablespoon. Sauté diced onion until golden, then add minced garlic and cook for an additional minute.

Deglaze the pot with ½ cup of bourbon, scraping the bottom to lift browned bits. Add balsamic vinegar, brown sugar, Worcestershire sauce, bay leaves, and beef broth.

Return the short ribs to the pot, ensuring they are submerged in the liquid. Cover and bake for 2.5 to 3 hours, basting every hour until fork-tender.

Meanwhile, prepare the horseradish sauce by whisking together sour cream, horseradish, Dijon mustard, lemon juice, salt, and cracked black pepper. Thin as needed with heavy cream.

Remove the ribs from the oven and let them rest for a few minutes. Serve with reduced braising liquid and horseradish sauce.