Mix the flour, sugar, water, yeast, and salt to form a loose dough. Knead the dough for 10 minutes by gripping it and slapping it against the side of the mixing bowl. Put the dough into a clean, greased plastic bag and knot closed. Place in a warm area for about one hour, or until doubled in size.
Place a steamer over a saucepan of simmering water. Put the bag containing the dough inside the steamer and steam for one hour, or until a skewer inserted comes out clean.
Remove from the saucepan and cover with a tablecloth and place in an open bowl.
