Sift flour and baking powder into the mixing bowl of an electric mixer. Add instant yeast, sugar, oil and alkaline water. Fit with a dough hook and process at low speed for a minute. Gradually add in water and continue to process at medium speed for 4-5 minutes until a smooth dough is formed.
Remove dough onto a lightly floured tabletop and knead for 3-4 minutes. Cover dough with a damp tea towel and allow to rise until it doubles in bulk. Cut dough into equal pieces of about 50g each. Cover with a piece of cling film and set aside for 2-3 minutes.
Roll the pieces of dough into a ball, then flatten with the palm of your hand. Brush one half of the flattened dough with corn oil. Fold over into a half moon shape. Use a spatula to cut the half moon shape dough on the edge to resemble a split flower.
Steam the buns over high heat for 15 minutes. Serve while still soft and warm.