Preheat your oven to 300F.
Season the short ribs with salt & pepper.
Add the olive oil to a Dutch over medium heat, and once the pot is hot, sear half the short ribs for about 3-4 minutes/side or until nicely browned. Transfer to a plate and then repeat for the second batch. The ribs may release a lot of fat, and if they do, spoon some of the excess fat out, leaving about 1-2 tablespoons in the pot.
Add the carrots and onions to the pot and sauté for 6-8 minutes or until they start to lightly brown.
Stir in the garlic and tomato paste and cook for about a minute.
Add the red wine, Worcestershire sauce, brown sugar, smoked paprika, Italian seasoning, salt, pepper, and thyme to the pot. Give it a stir, scraping up any browned bits from the bottom of the pot, and bring it to a simmer. Add the short ribs in as even of a layer as possible (some will likely stick out and that's ok). Cover and transfer to your oven and cook for 3-3.5 hours (the meat should be falling off the bone).
Once the ribs are done, skim the fat off the surface (I just use a spoon to do this... don't worry about getting it all). Mix the cornstarch with 2 tablespoons of cold water until you've got a smooth mixture, then stir it into the pot. The sauce should thicken up right away but you can always bring it to a boil on the stove to activate the cornstarch if needed. Give it a taste and season with extra salt & pepper as needed.