My grandmother's recipe for champagne mustard requires the dry mustard powder to be soaked in champagne/vinegar overnight. Is there a reason for this? My only guess is the original recipe used mustard seed, not powdered.
Soak overnight: 1 cup dry mustard
½ cup cider vinegar
½ cup champagne
Stir in: ½ cup brown sugar
Bring to boil. Simmer until thick.