There are actually two ways to make Japanese white sauce. The first uses store-bought mayonnaise. The second involves making your own mayonnaise. The end result tastes the same if you do it properly. I find it a lot easier to use prepared mayonnaise. The sauce is less likely to separate with store-bought mayonnaise, as Hellmann’s has years of practice getting it right.
1-1/4 cup Hellmann’s mayonnaise *
1/4 cup water
1 teaspoon tomato paste
1 tablespoon melted butter
1/2 teaspoon garlic powder
1 teaspoon sugar
1/4 teaspoon paprika
dash cayenne pepper
Using a fork or a whisk, blend all ingredients together thoroughly until well mixed and the sauce is smooth. Refrigerate overnight to allow flavors to blend. Bring to room temperature before serving.
The sauce will NOT taste right if you don’t let it sit overnight. And please don’t try to substitute ketchup for the tomato paste! The water is needed to bring this to the right consistency.
I don’t know how long this keeps in the refrigerator; I’ve kept it 7-10 days, but I always wind up eating it all before 10 days so after that – anyone’s guess.
* Hellmann’s is called “Best Foods” west of the Rockie Mountains. Use other mayos at your own risk – many cheap brands make the sauce taste too much like mayo.