Beer mustard is a prepared mustard made by blending ground mustard seed with beer, vinegar, and seasonings, giving it a tangier, richer flavor than standard prepared mustard.
It's associated with beer-drinking and pub traditions in Germany and the UK, and is commonly served with sausages, pretzels, and grilled meats. Lighter beers give a milder result; darker beers like stouts add roasted, malty depth. Beyond its use as a condiment, beer mustard also works in marinades, dressings, and glazes for roasted meats.