Preheat oven to 300° Fahrenheit.
Pat ribs dry with a paper towel and season generously with kosher salt and ground black pepper. Let rest for 30 minutes on a baking rack.
Heat canola oil or olive oil in a large Dutch oven over medium-high heat. Lightly dust all sides of the short ribs with all-purpose flour.
Once the oil is hot, add the beef short ribs and sear for a few minutes on each side. You may need to work in batches so you don't crowd your pot. Once browned, remove ribs from the pot and set aside.
Add mirepox (onion, celery and carrots) and few pinches of salt and pepper to the dutch oven. Sautee until tender and almost caramelized (about 10 minutes). Once tender, add the garlic, bouillon beef base and tomato paste. Stir well and sauté for another 1-2 minutes.
Pour in the red wine vinegar and scrape the brown bits from the bottom of the pot. Pour in the beef stock then add the short ribs, rosemary, thyme and bay leaves to the braising liquid.
Let the liquid come to a low simmer. Once simmering, cover the pot with a lid and transfer to preheated oven. Let short ribs braise for 3-3½ or until they are fall off the bone tender.
Remove meat and vegetables from the Dutch oven and place them on a platter using a slotted spoon. Cover with foil to keep warm. Skim fat from braising liquid. Discard bay leaf, rosemary and thyme.
Bring the remaining braising liquid to a boil. In a small bowl, mix cornstarch with water until smooth. Pour into the braising liquid stirring constantly until thickened, 2-3 minutes.
Pour over short ribs or serve on the side. Taste and adjust seasonings as necessary.