Place the dry vermicelli noodles in a bowl and cover them with boiling hot water.
Allow the noodles to soak for 7 to 8 minutes, or until softened and cooked.
Drain the noodles thoroughly.
Roughly chop the noodles into small pieces, approximately 1/2 inch long.
Heat a pan over medium-high heat.
Add 1 tbsp neutral oil to the pan.
Once the oil is hot, add the chopped scallions or chives, shredded carrots, and shredded cabbage.
Cook for 4 to 5 minutes, stirring frequently, until the carrots are tender and the cabbage has softened.
Add the chopped vermicelli noodles to the pan.
Add the soy sauce, salt, roasted sesame seeds, and toasted sesame oil.
Stir well with a wooden spoon or spatula until the filling is evenly combined.
Continue cooking for 2 to 3 minutes over medium heat.
Taste the filling and adjust the seasoning if necessary.
Transfer the filling to a strainer to drain any excess liquid.
Set the filling aside to cool completely before assembling the buns.