Combine half of the minced ginger and one-third of the chopped green onions in a bowl. Add 150ml warm water and let steep for 10 minutes. Strain and reserve the liquid.

In a large bowl, mix ground pork with all seasonings (salt, peppers, soy sauces, oyster sauce). Gradually add the aromatic liquid, stirring in one direction until fully absorbed. Mix in remaining ginger and green onions, then the oil. Refrigerate while preparing dough. Just before wrapping, mix in the chopped Napa cabbage (squeezed dry if using blanched).

Combine flour, yeast, and sugar in a bowl. Gradually add lukewarm water while stirring until a shaggy dough forms. Knead for 5-8 minutes until smooth and elastic. The dough should be soft but not sticky.

Divide dough into 12-15 equal pieces (about 40g each). Roll each into a ball, then flatten into a 3-inch circle, keeping edges slightly thinner than center. Place about 2 tablespoons of filling in the center, then pleat and seal firmly.

Place shaped buns on a tray, cover with a damp cloth, and let rest at room temperature for 25-35 minutes until visibly puffed up.

Heat oil in a large non-stick skillet over medium-low heat. Arrange buns in the pan, leaving space between them. Fry for 3-4 minutes until bottoms are golden brown.

Carefully pour in hot water (it will sizzle!), immediately cover, and steam for 8-10 minutes until water evaporates.

Uncover and continue cooking for 2-3 minutes until bottoms re-crisp. Garnish with sesame seeds and green onions.

Serve immediately while bottoms are still crispy!