Finding a substitute for the grainy texture, zippy flavor and tangy zing of whole-grain mustard is no easy feat. Whole-grain mustard is composed of coarsely ground mustard seeds, spices and wine or vinegars for an acidic punch. The bolder texture of this mustard adds bite to sandwiches, cold cut platters and even salad dressings. When looking for a replacement because your cupboard is bare or you're allergic, look for choices that offer the same textural and taste substitutions.
Horseradish, a root you can purchase fresh in some large stores or jarred, can serve as a heated substitute. It won't duplicate the flavor directly, but fresh or jarred, shredded or grated versions that are packed in water will add a natural heat and tang that are reminiscent of mustard. Fresh horseradish grated and blended with a bit of fresh or sour cream spreads easily on a sandwich and offers the grainy texture that the mustard would have provided.
If you're simply out of whole-grain options, but not mustard-averse altogether, opt for another type of mustard instead. When subbing with an alternative mustard, consider the flavor profile. If the dish benefits from a slightly sweet addition, honey mustard may sub in well.
A dash of ground cayenne pepper or wasabi power can duplicate the heat, but not the texture, of whole-grain mustard. Use one of these options when the mustard adds a pleasant heat to dishes, such as salad dressing or dip, but you don't need the textural boost. Beware, though, that these powders carry considerably more heat power than many mustards and you'll need to adjust the amount added according to your taste.