Nevertheless, I had fun on my weekend adventures in har gow and mochi-making.
The "skin" of the har gow is made from tapioca and wheat starch.
I was afraid the dough would be sticky or difficult to work with, but the texture was actually quite springy and didn't stick at all.
I had neither a rolling pin or a heavy pot, though, and getting the "skin" to the right thin-ness is the most important part about good har gow. Thinness and shape...with practice!
Mochi is made with yet another type of flour -- glutinous rice flour ("mochiko"). This is sweet, or sticky, rice ground up into a white powdery substance not unlike tapioca or wheat starch. It is mixed with sugar and water. The resulting textures are very interesting: before cooking, the above is actually pretty watery. As for after cooking...
...it's fairly difficult to work with! (ever seen videos of Japanese men taking huge mallets to mochi?). I would definitely work with smaller quantities if I attempt mochi again in the future.
Above: my first, much misshapen but much-loved mochi containing a white chocolate-covered raspberry. I also left some mochi plain, to eat with ice cream at a later date. Stressful cookery, but yum!