Place the yeast in a bowl and pour the warm water over. Stir in the sugar to dissolve. Let stand for 15 minutes.
Sift the flour into a bowl. Add the yeast and water mixture and begin stirring immediately.
Keep stirring until you have a dough that holds together and doesn’t stick to the sides of the bowl. Adjust the amount of water, adding more or less as is needed.
Turn the dough out onto a lightly floured surface, and knead until it is smooth and elastic (about 10 minutes). Add more flour or water if needed.
Cover and let rest for 1 1/2 hours. Punch the dough down again, and let it rest for 1 – 1 1/2 more hours, until it’s size has doubled.
Steam, tightly covered, over briskly boiling water for 10 minutes. Serve.