Heat up water or milk in a microwave for 30s. It should be hot but not unbearable to the touch. Dissolve sugar and oil and sprinkle yeast on top. Let rest for 5 minutes or until foamy.
Combine together flour and baking powder. Mix flour mixture into the yeast mixture and knead until a smooth and elastic dough forms. Let rest for 1 hour.
Prepare your steamer with parchment paper, steaming cloth/liner.
Transfer the dough onto a work surface and divide it into 10 equal pieces. One by one roll it out into a rectangle. Place a sausage piece at one end and cut thin vertical lines along the other. Press the edges of the cut side down (this will help with sealing the crease).
Roll up the sausage and transfer it to a steam basket seam side down. Cover the steam basket and let the dough proof for 30-60 minutes.
Add water to a pot and turn your stove on high. Place the steam basket on top and steam for about 10-12 minutes. Turn off the heat and let the buns sit, covered, for about 5 minutes before serving.
Storage: You can freeze the buns once they have cooled. To reheat, just pop it back into the steam basket and repeat the steaming step.