Pat short ribs dry and season evenly with 1 tablespoon kosher salt and 1 teaspoon freshly ground black pepper. Heat a large Dutch oven or heavy-bottomed pot over medium-high heat and add 2 tablespoons vegetable oil. When shimmering, sear short ribs in batches (2–3 minutes per side) until deeply browned. Transfer ribs to a plate.

Sweat vegetables

Reduce heat to medium. Add chopped onion, carrot, and celery to the pot and cook, stirring occasionally, until softened and beginning to brown, about 6–8 minutes. Add smashed garlic and 2 tablespoons tomato paste and cook 1–2 minutes until tomato paste darkens in color.

Deglaze and braise

Pour in 1 cup red wine to deglaze, scraping up browned bits from the bottom. Let wine reduce by half over 3–5 minutes. Return short ribs to the pot and add 3 cups beef stock, 3 thyme sprigs, and 2 bay leaves so the liquid comes about 3/4 of the way up the ribs. Bring to a gentle simmer, then cover, reduce heat to low, and braise on the stovetop for 2 to 2 1/2 hours, or transfer to a 325°F (160°C) oven and braise 2 to 2 1/2 hours, until meat is fall-apart tender.

Shred meat and strain sauce

Remove short ribs and set on a cutting board to cool slightly. Skim fat from the surface of the braising liquid, then strain vegetables, reserving the liquid. Shred the short rib meat with two forks discarding bones and excess fat. Measure out about 2 cups shredded meat for sandwiches; reserve any extra for another use. If the braising liquid is thin, simmer the reserved liquid over medium heat until reduced and slightly thickened (about 8–10 minutes) and spoon 1–2 tablespoons over the shredded meat to keep it moist.

Creamy Horseradish Spread

Whisk together 3 teaspoons prepared horseradish, 1 tablespoon mayonnaise, 2 tablespoons sour cream and 1 teaspoon lemon juice in a small bowl. Season with a pinch of black pepper and taste; add more horseradish if you want more heat. Refrigerate until ready to assemble. This yields enough for 4 sandwiches (8 slices).

Sandwich Assembly & Grilling

Assemble sandwiches

Spread a thin layer of the creamy horseradish on the inside face of four bread slices. Top each horseradish-spread slice with an even layer (about 1/2 cup) of shredded braised short rib. Add about 2 ounces (approx. 2 slices or a small handful if shredded) Havarti Dill on top of the meat. Sprinkle 3/4 teaspoon of crispy fried onions over the cheese. Top with the remaining bread slices, plain side out.

Butter and grill

Spread softened butter evenly on the outside faces of the assembled sandwiches. Heat a large skillet or griddle over medium-low to medium heat. Place sandwiches in the pan and press gently with a spatula or a weight. Cook 3–4 minutes per side, lowering heat if the bread is browning too quickly, until bread is golden brown and cheese is melted. Flip carefully and continue to cook until both sides are crisp and cheese is fully melted. Total grilling time should be 6–8 minutes per sandwich pair.

Rest and serve

Transfer sandwiches to a cutting board and let rest 1–2 minutes, then slice each sandwich in half. Serve immediately, optionally with extra braising jus on the side for dipping and an extra dollop of the horseradish spread. Pairs well with a Syrah.