In a small mixing bowl combine garlic salt, black pepper, and 1 tablespoon of the olive oil. With gloved hands, rub the mixture all over the oxtails.
Pour remaining olive oil into the Dutch oven. Heat olive oil over medium-high heat until shimmering. Brown oxtails on both sides in hot oil, until a nice brown crust has formed. Remove from pan.
Deglaze the pan with red wine, stirring and gently scraping the brown bits off the bottom. Bring to a boil.
Add garlic, celery, onions, carrots, ketchup, beef base, and water.
Using tongs, add the oxtails into the pot, nestling them all in. If they are still poking out above the liquid level, add more water until they are covered.
Add rosemary sprigs to the liquid in the pan, gently pressing them just below the surface.
Place cover on Dutch Oven and turn heat down to low. Simmer for 3 hours, checking halfway through to see if more liquid needs to be added. Keep the liquid level just above the meat.TIP: if you do need to add more liquid, add hot water.
Carefully remove oxtails from the pan and tent with foil to keep warm. Skim excess fat from the top with a spoon (or you can pour the liquid through a fat separator.
Good dry red wine options for braising include cabernet sauvignon, merlot, malbec, or zinfandel. However, expensive wines are not necessary. I would suggest using what you have on hand or what you enjoy sipping on as you'll only be using 1 cup worth of wine.
We use a concentrated buillon base for most of our recipes instead of broth or stock. It’s convenient, takes up a lot less space, and is easily reconstituted with water. You can certainly use broth or stock instead. If you don’t use base, replace the water with beef broth.
To thicken the sauce you can make a slurry from 2 teaspoons of cornstarch and 1/4 cup water, mix into the liquid in the pan and simmer until thickened.