They're cooked in a covered pan with a splash of milk and no added fat until the bottoms caramelize into a crisp, sugary crust while the tops stay pillow-soft — one bun, two textures.
Sweet yeast dough is formed into rolls and steamed in a tightly covered pot over a milk-and-butter mixture until the bases turn golden and crackly. Market stalls and street bakeries serve them warm with vanilla sauce or dusted with sugar, sometimes in a savory version alongside soup.