<<Disclaimer: Verify this information before applying it to your situation.>>

I'm sure you all think you have read enough about mustard, but I've been
traveling and just read most of the messages in one exhausting batch.  Dry
mustard powder is mentioned as perhaps containing wheat flour.  There is a
simple way to avoid that.  Buy mustard seeds and grind your own. Any coffee
grinder will do the trick. GK