Pat the beef chunks dry with paper towels. Season evenly with 2 tsp kosher salt and 1 tsp black pepper. Toss the beef in 2 tablespoons flour until pieces are lightly coated; shake off excess.

Brown the beef

Heat a large heavy-bottomed Dutch oven or ovenproof pot over medium-high heat. Add 2 tablespoons neutral oil and 1 tablespoon butter. When hot and shimmering, add beef in a single layer (work in batches to avoid crowding). Sear until deeply browned on all sides, about 3–4 minutes per side. Transfer browned beef to a plate and repeat until all beef is browned.

Sauté aromatics

Reduce heat to medium. Add the diced onion, sliced carrots, and celery to the pot. Sauté, stirring, for 6–8 minutes until softened and starting to brown. Add smashed garlic and 1 tablespoon tomato paste and cook 1–2 minutes, stirring, until the paste darkens slightly.

Deglaze

Pour in 1 cup dry red wine to deglaze the pot, scraping up brown bits from the bottom with a wooden spoon. Let the wine simmer for 2–3 minutes to reduce slightly and burn off most alcohol.

Add liquids and aromatics

Return the browned beef and any accumulated juices to the pot. Add 2 cups beef stock, 1 teaspoon Worcestershire sauce, 3 sprigs thyme, and 1 bay leaf. The liquid should come about halfway up the beef; add up to 1/2 cup additional stock or water if necessary.

Braise

Bring to a gentle simmer on the stovetop, then cover and transfer to a 325°F (160°C) oven. Braise until the beef is fork-tender and easily shredded, about 2 to 2½ hours. Check once at about 1½ hours — if liquid is low, add a splash of stock. Alternatively, continue simmering gently on the stovetop over low heat, covered.

Finish the braise

When beef is tender, remove pot from oven. Transfer beef to a cutting board and shred or chop to desired size. If you prefer a thicker sauce, place the pot back on medium-high heat and simmer uncovered for 5–10 minutes to reduce and concentrate flavors; skim any excess fat. Taste and adjust seasoning with salt and pepper.

Horseradish Crema

While the beef is braising (or during the last 30 minutes), whisk together 1 cup sour cream, 2 tablespoons prepared horseradish, 1 teaspoon fresh lemon juice, 1 teaspoon Dijon mustard, 1 teaspoon salt, and 1/2 teaspoon freshly ground black pepper in a small bowl until smooth. Taste and adjust horseradish or lemon for brightness. Chill until ready to serve.

Bread & Finish (Assemble)

Toast the rolls

Split the 4 yeast rolls or ciabatta and brush cut sides lightly with softened butter, if using. Toast cut-side down on a skillet over medium heat or under a broiler until golden and crisp, about 1–2 minutes in a skillet or 2–3 minutes under a broiler. Keep warm.

Assemble Beast on Yeast

Pile a generous portion of shredded braised beef onto each toasted roll. Spoon or dollop 1–2 tablespoons horseradish crema over the beef. Add optional pickled red onion (about 2 tablespoons per sandwich) and sprinkle with chopped parsley. Serve immediately, passing extra crema and braising sauce on the side.

Leftover sauce

Stir any reserved braising sauce back into the shredded beef before filling for juicier sandwiches, or serve it alongside as a dipping jus.