Braised Beef Short Ribs

4-1/2 to 5 lb. English-style beef short ribs (8 to 12 ribs)
3 Tbs. vegetable oil
Kosher salt
ground black pepper
2/3 cup medium-diced onions
2/3 cup medium-diced carrots
2/3 cup medium-diced celery
1 Tbs. finely chopped garlic
1 Tbs. chopped fresh thyme
2 whole dried bay leaves
1/2 cup dry red wine
1-1/2 cup diluted lower-salt beef broth (mix equal parts broth and water)
1-1/2 cup dry red wine
1 to 2 tsp. balsamic vinegar
1 to 2 Tbs. chopped fresh parsley

Position a rack in the center of the oven and heat the oven to 325°F. In an 8-quart Dutch oven, heat 2 Tbs. of the oil over medium heat. Season the ribs with 2 tsp. salt and 1 tsp. pepper. Add half of the ribs to the pot (or as many as will fit without overlap), and cook, turning with tongs, until nicely browned on all sides, 3 to 4 minutes per side. Transfer the ribs to a platter and repeat with the remaining ribs. Pour off all but a thin layer of fat from the pan.
Add the remaining 1 Tbs. oil, onions, carrots, and celery to the pan. Season with 1/2 tsp. salt. Cook, stirring and scraping up any browned bits on the bottom of the pan, until the aromatics are soft and lightly browned, 6 to 8 minutes. Add garlic, thyme, and bay leaves, and cook, stirring, until well distributed and fragrant, about 1 minute.

Pour the 1/2 cup red wine into the pot and cook, stirring to scrape up any browned bits on the bottom of the pot, until the liquid is reduced to about 2 Tbs., about 1 minute.

Transfer all the ribs (and any juices that have accumulated) back into the pot. Pour the beef broth and red wine and 1 cup water over the ribs and using tongs, arrange the ribs as evenly as possible and no more than two layers deep.
Bring the liquid to a simmer, cover, and put the pot in the oven. Cook, turning the ribs with tongs about every 40 minutes, until they are fork tender, about 2-3/4 hours. (The meat may fall off most of the bones about midway through cooking; this does not mean that the ribs are fully tender.)

Transfer the ribs to a serving platter or dish. Let the sauce and solids sit in the pot for a few minutes to cool and with a shallow spoon, skim off as much of the fat as possible from the surface. Season the sauce to taste with salt and pepper, and add the vinegar.

Serve the ribs with the sauce spooned over, sprinkled with chopped parsley. Serves 6.