In a small bowl, combine warm water, sugar, and yeast. Let stand for 5-10 minutes until foamy and active.

In a large mixing bowl, combine flour and salt. Pour in the yeast mixture and vegetable oil. Mix until a shaggy dough forms.

Knead the dough on a floured surface for 10-12 minutes until smooth and elastic. Place in an oiled bowl, cover with a damp cloth, and let rise in a warm place for 1-1.5 hours until doubled in size.

While the dough rises, prepare the filling. In a large bowl, combine ground pork, cabbage, green onions, soy sauce, sesame oil, oyster sauce, ginger, garlic, sugar, white pepper, five-spice powder, and cornstarch. Mix thoroughly in one direction until the mixture becomes slightly sticky and well combined.

Once the dough has risen, punch it down and divide it into 12 equal portions. Roll each portion into a ball.

Roll each ball into a 4-inch circle, keeping the edges thinner than the center.

Place about 2 tablespoons of filling in the center of each circle. Pleat and pinch the edges together, twisting slightly to seal completely.

Place each bun on a small square of parchment paper. Cover and let rest for 20-30 minutes for a second rise.

Fill a steamer or wok with water and bring to a boil. Arrange buns in the steamer basket, leaving space between each one as they will expand.

Steam over high heat for 15-18 minutes. Do not open the lid during steaming.

Turn off heat and let buns rest in the closed steamer for 3 minutes before removing.

Serve hot with soy sauce, chili oil, or your favorite dipping sauce.