Prepare the Beef: Season cubed beef with rosemary salt and black pepper on all sides.
Sear the Beef: In a preheated pan on medium-high heat, add a little neutral oil and sear the beef cubes until they have a deep brown color on all sides. Remove from pan and set aside.
Cook the Tomato Paste: In the same pan, add tomato paste and cook off on medium heat, stirring every 30 seconds, for about 3-4 minutes until the flavor deepens.
Build the Sauce: In a Dutch oven or large pot, add olive oil and butter, then cook carrots, onion, and celery with a pinch of rosemary salt and more black pepper for about 8 minutes. Add thyme, chili flake, and the cooked tomato paste, then deglaze with red wine.
Add Tomatoes and Beef Stock: Mix in the crushed tomatoes and cook down for 5 minutes before adding the beef stock. Use some stock to deglaze the pan used for tomato paste, then add to the pot along with a little red wine vinegar.
Braise the Beef: Add the seared beef and any accumulated juices to the pot, ensuring the beef is submerged. Cook on a gentle simmer, partially covered, for 2.5 hours, adding water if needed.
Rest and Shred the Beef: Let the beef rest in the sauce for at least 30 minutes to an hour before shredding to desired consistency.
Cook the Pasta: Cook pappardelle pasta in salted boiling water until al dente, about 5 minutes.
Combine and Serve: Toss the cooked pasta with the beef ragu, garnish with Parmesan cheese and parsley, and serve immediately.