Preheat oven to 325°F (163°C). Pat short ribs very dry, then season generously all over with salt and pepper.

Heat oil in a large Dutch oven over medium-high heat. Sear ribs in batches until deeply browned on all sides, about 3-4 minutes per side. Transfer to a plate.

Reduce heat to medium. Add onion, carrots, and celery to the pot. Cook, stirring, for 6-8 mins until softened. Add garlic and cook 1 min more.

Stir in tomato paste and cook for 2 minutes. Sprinkle flour over vegetables and cook, stirring, for 1-2 mins.

Pour in red wine, scraping up all the browned bits from the bottom. Simmer until reduced by half, about 5 mins.

Add bourbon and simmer for 3-4 mins (flambé optional). Stir in balsamic vinegar and beef stock.

Return ribs and any juices to the pot. Liquid should come 2/3 up the sides of the meat. Add thyme, rosemary, bay leaves, and peppercorns. Bring to a bare simmer.

Cover tightly and transfer to the preheated oven. Braise for 2.5 to 3.5 hours, until meat is fork-tender and falling off the bone.

Transfer ribs to a plate, tent with foil. Strain braising liquid through a fine-mesh sieve into a bowl; discard solids. Skim fat from the surface.

Return defatted liquid to a clean saucepan. Simmer vigorously over medium-high heat until reduced by half and thickened to a glaze, 15-25 mins. Season to taste.

Serve ribs over mashed potatoes or polenta, spooned generously with the glaze. Garnish with zest, herbs, and flaky salt.