In a large bowl, combine all the dry ingredients. Add the water and oil. Combine until mixture forms a ball. Knead for 5 minutes or until dough is smooth.
Shape the dough into a ball and place into a greased bowl. Turn the ball to ensure it is thoroughly coated with oil. Cover with a humid cloth and let rest at room temperature for 2 hours, or until the dough has doubled in volume.
On a floured work surface, divide the dough into 18 balls. Using a rolling pin, flatten each ball into an oval shape. Using a pastry brush, baste the dough with a bit of oil.
Fold the dough onto itself to form a half-moon. Place each half-moon on a small piece of parchment paper and place on a baking sheet. Cover with plastic wrap or a clean cloth. Let the dough rise at room temperature for 30 minutes.
Put a bit of water in a pot and bring to a boil. Place a bamboo steam basket over the pot. Place a few buns, still on their parchment paper, into the basket, lower the heat to medium, cover, and steam-cook for approximately 12 minutes. Repeat until all the buns are cooked.