Hibachi -- the restaurants based on the showmanship of talented cooks preparing beef, seafood and vegetables for guests seated around a flattop grill -- offers a Japanese-style mustard that has a consistency similar to a creamy dipping sauce, and a spicy taste redolent of brown mustard. Although the ingredients for hibachi mustards vary from establishment to establishment, most are based on karashi, a traditional Japanese mustard made from powdered brown mustard seeds and wasabi. Hibachi mustards use mayonnaise to cut the spiciness of the karashi, and contain ingredients such as garlic and soy sauce for flavoring, a recipe you can easily recreate at home.
Mix a two-to-one ratio of karashi mustard powder to warm water in a mixing bowl to form a thick paste, or squeeze prepared karashi from the tube into the mixing bowl.
Cover the bowl with plastic wrap. Wait 10 minutes for the enzymes and the glycosides to react, indicated by a pungent, zesty aroma. Unwrap the bowl.
Add just enough mayonnaise to the karashi to make it spreadable and smooth, like a dipping sauce. You can also add mayonnaise until it reaches your desired consistency. Mix the mayonnaise and mustard until homogenized.
Add the mustard to a food processor and add aromatic ingredients and spices to taste. Most Japanese mustards you find in hibachi-style restaurants contain soy sauce, garlic and sugar. But don't limit yourself. Try fresh ginger, green onions, green garlic, sesame seeds and miso for your own interpretation.
Process the mustard until smooth and homogenized, then taste it. Adjust the taste as needed with salt or aromatic ingredients and transfer the mustard to the serving dish. Serve the hibachi mustard immediately.