Season the short ribs with salt and pepper covering all sides of the meat.
Heat the oil in a large Dutch oven over medium heat and sear the ribs in batches, 2 to 3 ribs at a time, searing each side for about 45 seconds. Transfer to a plate and finish searing the rest of the meat.
Remove some of the excess oil/fat from the Dutch oven, making sure to leave some. Add the celery, onions, shallots, and carrots and saute until soft and translucent, about 5 minutes.
Add in the flour, salt, tomato paste, garlic, mustard powder, and red pepper flakes and stir frequently for about 1 minute.
Add in the wine and use your spoon to scrape and deglaze the bottom of the pot. Add the ribs back in and spoon the wine over them, then allow them to simmer and the wine to reduce for about 20 minutes. Meanwhile, preheat oven to 350°F.
Add in the beef stock and herbs then cover and bake in the oven for about 2 hours and 45 minutes. The meat should be falling off the bone when done.
Once done cooking, remove the ribs. Skim the excess fat off of the top of the sauce, remove the bay leaves and discard fat and bay leaves.