Mustard is an excellent and surprisingly subtle flavoring for mayonnaise. When used in small amounts, it brightens the flavor of the mayonnaise while remaining in the background. Any variety of mustard can be used. Maille brand Dijon mustard, homemade mustard, and whole-grain Meaux-style mustard all provide different nuances. Green mustard, sold by Maille, is colored with chlorophyll and can also be used for color and flavor. Flavored mustards can be used in mayonnaise, but a better flavor is often obtained by adding the fresh flavor component directly to the mayonnaise instead of relying on the mustard to provide it. For example, tarragon-flavored mustard will not provide as clear and bright a flavor as mayonnaise flavored with plain mustard and fresh tarragon. The total amount of mustard to use—including any that was added when preparing the mayonnaise base—depends on the strength of the mustard and the whim of the chef, but 4 teaspoons (20 milliliters) per cup (250 milliliters) mayonnaise is a good place to start.