In a large mixing bowl, combine all-purpose flour, instant dry yeast, sugar, and salt. Create a well in the center and gradually pour in warm soy milk and toasted sesame oil. Mix until a sticky dough forms, then knead for about 8–10 minutes on a floured surface until smooth and elastic. Place the dough in a lightly oiled bowl, cover it, and let it rise in a warm spot for 1–2 hours, or until it doubles in size.

While the dough rises, soak the vermicelli noodles in boiling water for around 5 minutes until soft. Drain and chop the noodles into smaller pieces. In a heated skillet over medium-high heat, add a drizzle of oil and sauté the raw shredded cabbage, finely shredded carrot, and chopped scallions for about 3–4 minutes until tender. Stir in the chopped noodles and soy sauce, cooking for an additional minute to combine flavors, then set the filling aside to cool.

Once the dough has risen, punch it down to release air and transfer it to a floured surface. Divide the dough into 12-16 equal pieces and roll each piece into a ball. Using a rolling pin, flatten each ball into a thin circle about 3–5 inches in diameter.

Spoon 2-3 tablespoons of the filling into the center of each dough circle. Carefully fold the sides of the wrapper over the filling and pinch the top together, twisting it to seal securely. Place each sealed bun on a lightly floured tray, ensuring they aren't touching, and allow them to rest for about 15 minutes to rise slightly.

In a large, non-stick skillet, heat a couple of tablespoons of oil over medium heat. Arrange the buns in the skillet, placing them crease-side down, and fry for about 3–4 minutes until the bottoms are crispy and golden brown. Carefully add half a cup of water to the skillet and immediately cover with a lid. Allow the buns to steam for 5–6 minutes, until cooked through and tender.

When the buns are done cooking, carefully remove them from the skillet and let them cool slightly on a plate. Serve warm, or store any leftovers in an airtight container.