In a nonreactive container, combine mustard seeds with alcohol (beer, wine, or sherry; according to recipe) and vinegar. Let sit 48 hours.
Check periodically to make sure seeds are covered by liquid; add more if necessary.
Transfer seeds and liquid to a food processor. Add remaining ingredients.
Process until seeds become creamy, 4 to 6 minutes.
Ladle into hot jars and leave 1/2" headspace water bath for 15 minutes. .
Wait 5 days before using