Lay the short ribs meaty side up in a large roasting pan and season with salt and pepper. Scatter the carrots, celery, onion, garlic, bay leaf, and rosemary around the ribs. Add the chicken broth and vinegar. Set the pan directly over 2 burners and bring to a simmer over high heat. Lay a sheet of parchment paper over the ribs and transfer to the oven. Cook until the meat is fork-tender, about 2 hours. Remove from the oven and cool in the liquid, about 30 minutes. (The dish can be prepared up to this point 1 day ahead, covered, and refrigerated.)
For the coating: Whisk the mustard with the honey, water, and 1/2 teaspoon of the salt. Pulse the bread to make coarse breadcrumbs in a food processor. Add the garlic, parsley, olive oil, remaining 1/2 teaspoon salt, and the pepper, to taste, and pulse briefly to combine. Transfer mixture to a shallow bowl.
Preheat the oven to 450 degrees F.
Remove the ribs from the braising liquid (reserve liquid for other uses) and pat dry. Brush the meaty side of each rib with some of the mustard mixture, then press it into the breadcrumb mixture to coat. Arrange the ribs on a baking sheet and roast until the breadcrumbs are brown and crisp, 20 to 25 minutes. Serve the ribs hot or at room temperature.
English-style short ribs are pieces of individual longish short ribs¿not to be confused with flanken, which are thin, short pieces of rib that are connected by meat.