In a mixing bowl, combine the all-purpose flour, baking powder, sugar, and salt. Mix well to evenly distribute the dry ingredients. Create a well in the center of the dry ingredients and pour in the warm water and vegetable oil.
Stir the mixture with a spoon or spatula until it starts to come together. Once the dough comes together, transfer it onto a lightly floured surface and knead for about 5 minutes until it becomes smooth and elastic. Add more flour if the dough is too sticky.
Place the dough back into the mixing bowl and cover it with a clean kitchen towel. Let it rest for 10-15 minutes to allow the gluten to relax.
After the resting time, divide the dough into small portions and shape each portion into a round or oval bun. You can make them as big or small as you like.
Prepare your steamer by bringing water to a boil. Line the steamer with parchment paper or steamer liners to prevent the bread from sticking.
Place the shaped dough buns onto the prepared steamer, leaving some space between them as they will expand during steaming.
Steam the bread buns for about 12-15 minutes or until they are cooked through and puffed up.
Once cooked, remove the steam bread from the steamer and let them cool slightly before serving.