<<Disclaimer: Verify this information before applying it to your situation.>>
 
For those that are living near an IKEA, they have a Swedish specialty foods
shop that includes potato flour, and possibly some other GF foodstuffs. The
person writing about this in rec.food.cooking also bought some hartshorn (a
mixture of ammonium bicarbonate and carbamate). It is an older form of
baking soda. But no one has yet posted how to use it.
 
Don Wiss.