Activate the yeast: whisk warm soy milk, sugar, and yeast in a small bowl. Wait 5–10 minutes until frothy.

Make the dough: in a large bowl, whisk flour and 1/2 tsp salt. Add the yeast mixture and 1 tbsp toasted sesame oil. Mix into a shaggy dough. Turn out and knead for 8–10 minutes until smooth and slightly elastic.

First rise: oil a bowl, place the dough inside, cover with a damp towel or plastic wrap, and let rise in a warm spot until doubled, about 1–1.5 hours.

Soak vermicelli in hot water per package directions, then drain and chop roughly if long.

Heat neutral oil in a skillet over medium-high heat. Add shredded cabbage and carrot. Sauté until wilted and any liquid has mostly evaporated, about 6–8 minutes.

Add soy sauce, 2 tsp salt (adjust to taste), chopped scallions, and the cooled vermicelli. Stir in 2 tbsp toasted sesame oil. Cool the filling before assembling.

Punch down the dough and divide into 18–20 equal pieces. Roll each into a ball, then flatten into a round about 3.5 inches wide.

Place 1–2 tablespoons of filling in the center. Pleat the edges and pinch the top to seal.

Heat a nonstick or cast-iron skillet over medium heat with a thin film of oil. Place buns seam-side down and fry for 3–4 minutes until the bottoms are golden.

Add about 1/4 cup water per 6 buns to the pan and immediately cover. Steam for 6–8 minutes until cooked through.

Remove the lid and cook for 1–2 minutes to crisp the bottoms again if needed.

Brush each bun with toasted sesame oil and sprinkle roasted sesame seeds on top.