Combine warm water, active dry yeast, and granulated sugar in a bowl; let sit until frothy.

Mix gluten-free flour into the yeast mixture until a sticky dough forms.

Knead dough on a floured surface for 5-7 minutes and let it rise for 1 hour.

Heat sesame oil, sauté garlic and ginger, then add napa cabbage and carrot until tender, then incorporate ground pork (or mushrooms) until browned. Stir in soy sauce and rice vinegar, then cool filling.

Shape the dough into discs, fill them with the mixture, and seal by pleating.

Steam the buns over boiling water for about 8 minutes, let them rest before serving.

Serve warm, optionally garnished with sesame seeds.