Toss the julienned daikon radish and carrot with 3 tbsp unseasoned rice vinegar, 1 tbsp granulated sugar, and ½ tsp kosher salt in a bowl. Press down lightly, cover, and refrigerate while you prep everything else. The longer it sits, the better — even 20 minutes makes a difference.

Pat the pork belly cubes completely dry with paper towels — this is non-negotiable for crispy edges. Season generously with salt and pepper.

Heat 1 tbsp neutral oil in a large cast iron or heavy skillet over medium-high heat until shimmering. Sear pork belly cubes on all sides until deeply golden and the fat has rendered, about 8-10 minutes total. Work in batches if needed — crowding kills the crust.

While the pork sears, whisk together the white miso paste, mirin, rice vinegar, brown sugar, soy sauce, toasted sesame oil, grated ginger, and minced garlic in a small bowl until smooth. Taste and adjust if you like more sweetness or heat.

Drain off all but 1 tablespoon of rendered fat from the skillet. Reduce heat to low, pour the miso glaze over the pork belly cubes, and add just enough water to come halfway up the pork (about ½ cup).

Cover and braise gently for 40-45 minutes, turning cubes occasionally, until the pork is fork-tender and the glaze has reduced to a sticky, caramel-like coating.

While the pork finishes, steam the mini bao buns according to package directions — typically 8-10 minutes in a bamboo or metal steamer lined with parchment. Keep them covered and warm until assembly.

Stir together the Kewpie mayonnaise and sriracha until smooth. Transfer to a small zip-lock bag and snip a tiny corner for drizzling — instant precision without the squeeze bottle.

Open each bao bun and lay it flat. Drain the pickled slaw and pile a small mound inside. Top with 1-2 glazed pork belly cubes, a zigzag of sriracha mayo, a scatter of sliced scallions, and a pinch of toasted sesame seeds. Serve immediately while the bao is pillowy and the pork is glistening.