Sake white sauce seafood gratin

I've seen a lot of Sake lees recipes on a Japanese cooking website, cookpad lately.
I found out why by reading this article about sake lees in Japan Times.
A popular Japanese science TV program introduced the health benefit of sake lees.

So I bought a bag of sake lees at a Japanese grocery store to try some of them.
Sake lees are the leftover from sake production and quite nutritious!
The most popular dish using sake lees is "kasuzuke" which is made by pickling fish in the lees. But today, I made sake white sauce for the gratin.

Sake white sauce

2tsp sake lees
1cup soy milk
1tbs miso
1tbs tahini
1tbs soy source
1tbs vinegar

Put the sake lees in a pot with soy milk and stir while heating over a medium low heat until the lees melt. Add the other ingredients and use as white source for gratin.