Preheat the oven to 300° F.
Season the rib meat with salt and pepper. Heat the oil in a large, heavy-bottomed, ovenproof pan over medium heat. Add the meat in batches and brown on all sides, about 8 to 10 minutes. Remove browned rib meat from pan and set them aside. Add the onion and garlic to the pan and cook, stirring frequently, for 2 minutes. Add the tomato paste, wine, and mustard. Bring the mixture to a boil, scraping the brown bits from the ribs into the mixture.
Return the rib meat to the pan and add the beef stock. Cover the pan, bring to a simmer, and place in the oven for 2-1/2 hours, until the meat shreds. Remove meat from the pan and remove any excess fat from the surface of the cooking liquid. Transfer the cooking liquid to the bowl of a food processor. Process until the mixture is a smooth sauce. Pour the sauce into a pan and keep warm over low heat.
Preheat the oven to 325° F.
Cut tortillas into 2-inch rounds. Fold a sheet of aluminum foil into a bending wave, creating a series of V shaped troughs to hold the tortillas in a taco shape. Or use a straight-line baking rack with half-inch pace in between, and slightly bend the taco shell to fit between the bars of the cooling rack. Place the 2-inch rounds in the “waves,” set on a sheet pan, and bake for 20 minutes or until crisp. Remove from oven and let cool. Repeat until all taco shells are baked.
Shred the short rib meat and lightly toss with the warm sauce. Fill each mini taco shell with a bit of meat and top with a bit of crumbled Roquefort and rosemary.
Short ribs can be used in many different ways, as shown in this and the following recipes. The braised short ribs will hold in your refrigerator up to 2 weeks and in your freezer up to 3 months in a properly sealed airtight container. Makes a good omelet mix.
Braised short ribs literally melt in your mouth. I love them as filling for homemade mini taco shells. The 2-inch tortillas are baked into shape using aluminum foil—so easy, and a real crowd pleaser! Serve with beer or red wine.
Use pork or veal for a variation on this dish. The thickness of the meat will determine how long you should cook it. For every inch of thickness, estimate 45–60 minutes, depending on your oven. You can substitute beer for the red wine; a dark stout will build up the earthy flavor of this dish.