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Mustard is prepared by grinding the seeds of the Mustard plant, and mixing them with water or vinegar. Depending on which seeds are taken, and/or how much vinegar is added, the mustard may turn out hotter or less hot.
Most mustard is made available as a bottled condiment and can be spread on a slice of sandwich bread or squirted onto a hotdog along with ketchup, horseradish and other spices. It is often found in fast-food restaurants in the form of a small packet which the diner may open and squeeze into the dish of choice.