Pat short ribs dry with paper towels and season all sides generously with salt. Let them sit at room temperature for 30 minutes before cooking.

Heat oven to 160 C / 320 F.

Heat oil in a 5-quart Dutch oven over high heat until shimmering. Sear short ribs in a single layer, fat-side down first, for 3 to 4 minutes per side until deeply browned on all four sides. Work in batches if needed. Transfer ribs to a plate.

Pour off all but 1 tbsp of fat from the pot. Reduce heat to medium. Add minced garlic and grated ginger and cook for 90 seconds, stirring constantly, until fragrant but not burnt.

In a bowl, whisk together gochujang, soy sauce, doenjang, brown sugar, gochugaru, sesame oil, beef stock, and rice wine until the pastes are fully dissolved.

Pour the gochujang liquid into the pot, scraping the bottom with a wooden spoon to lift any browned bits.

Return short ribs to the pot, bone-side up. Add bruised scallion halves and star anise. The liquid should come about halfway up the ribs. Add a splash more stock if needed.

Bring to a bare simmer, then cover with the lid slightly ajar and transfer to the oven.

Braise at 160 C / 320 F for 2 hours 15 minutes, then remove the lid fully for the final 45 minutes to allow the liquid to reduce and the meat to darken slightly.

Check doneness by pressing the thickest rib with tongs. The meat should feel very soft and pull away from the bone with gentle pressure. An instant-read thermometer should read at least 93 C / 200 F for full collagen breakdown.

Remove pot from oven. Transfer ribs to a cutting board and let cool for 10 minutes. Discard scallion halves and star anise.

Pull meat from the bones using two forks and shred into rough pieces. Discard bones and any large pieces of hard fat.

Strain the braising liquid through a fine-mesh sieve into a small saucepan, pressing on the solids. Skim visible fat from the surface.

Simmer the strained liquid over medium heat for 8 to 10 minutes until it coats the back of a spoon and is slightly syrupy. Taste and adjust seasoning with a pinch of salt or a few drops of soy sauce if needed.

Return shredded beef to the reduced sauce and toss to coat. Keep warm over low heat while you prepare the bao and pickles.

Combine rice vinegar, caster sugar, and fine salt in a small bowl and stir until dissolved.

Add sliced cucumbers and toss to coat. Let sit for at least 15 minutes at room temperature. They will soften slightly and turn bright and briny. Sprinkle with sesame seeds if using.

Line a bamboo steamer basket with small squares of parchment paper. Place frozen bao buns in the basket, spaced 2 cm apart. Set over a wok or pot of rapidly simmering water.

Steam with the lid on for 8 minutes until bao are puffed, soft, and no longer frozen at the center.

Gently open each bao and fill with a generous spoonful of sauced shredded beef. Add 3 to 4 cucumber slices, a pinch of sliced scallion greens, a few sesame seeds, a drizzle of sesame oil, and cilantro leaves if using.

Serve immediately while the bao are still warm and soft.