Pat the short ribs dry and season all over with salt and pepper. Sear in olive oil until browned on all sides, then remove to a plate.
Add carrots, celery, and onion to the same pot. Sauté until softened, then stir in garlic and tomato paste until fragrant.
Pour in red wine, scraping up any browned bits. Simmer until slightly reduced.
Add passata, beef broth, soy sauce, thyme, and bay leaf. Return ribs to pot, bring to a simmer, cover partially, and cook for 3 hours until tender.
Remove ribs, discard bones, and shred the meat. Return it to the pot. Skim off excess fat, then stir in heavy cream and Parmesan.
Boil pappardelle until al dente, drain, and toss in the sauce. Serve with parsley and more Parmesan.
