01 - Preheat oven to 325°F. Pat short ribs dry and season generously with kosher salt and black pepper.
02 - Heat olive oil in a large Dutch oven over medium-high heat. Brown short ribs on all sides, about 10 minutes, then transfer to a plate.
03 - Add chopped onion, carrots, and celery to the pot and cook until softened, approximately 5 minutes. Stir in minced garlic and tomato paste; cook for 2 minutes more.
04 - Pour in red wine, scraping up browned bits from the bottom. Simmer 3 minutes to reduce slightly.
05 - Incorporate beef broth, rosemary, thyme, and bay leaves. Return short ribs to the pot, ensuring they are submerged.
06 - Bring to a simmer, cover, and transfer to the oven. Braise for 2 hours and 30 minutes until meat is fork-tender.
07 - Thirty minutes before ribs finish, bring water and salt to a boil in a saucepan. Gradually whisk in cornmeal, reduce heat to low, and cook, stirring frequently, until thick and creamy, about 25 to 30 minutes.
08 - Stir unsalted butter and grated Parmesan into cooked polenta until smooth. Adjust seasoning if needed.
09 - Remove ribs from oven, discard herb stems and bay leaves, and skim excess fat from sauce. Serve ribs atop a generous portion of polenta, spooning braising sauce over.