Nattou tempura 納豆の天ぷら

Mr. Segawa 瀬川 of our Izakaya substitute "Tako Grill" has had a special "Izakaya menu" for some time. We have been enjoying items from this special menu. Occasionally, he adds more items to this menu or offers one-time only special items. One evening, he offered us "nattou tempura". We really liked it and I reproduced it here. I have seen other recipes for "nattou tempura" but this one is a very good one indeed.

Close up showing delicate and crunchy crust.

Nattou: I used one package of "hikiwari nattou" 挽き割り納豆 which was previously frozen. As usual, I added chopped scallion with mustard, and seasoning liquid came with the package of nattou. I mixed it well with my nattou stirrer (Left upper on the image below)
Perilla: Now we have our own perilla ("aojizo" 青じそ or "ooba" 大葉) growing in our herb garden, it is easy to get six good sized leaves. I washed and patted dry with a paper towel. I placed one teaspoonful of nattou in the middle (Upper right in the image below). I folded it in half. Since nattou is sticky it will remain folded (lower left in the image below).
Tempura batter: I simply used cake flour and cold Seltzer water to make rather thin tempura batter.
I coated the folded perilla leaves containing the nattou in the tempura batter and deep fried it in 170F vegetable oil for 3-4 minutes turning once (lower right in the picture below).

This was very good. My wife (she who in general does not like nattou)  liked it as well. The smell of nattou and the slimy/sticky texture were much reduced. I served this with a wedge of lemon and green tea salt. For this, definitely cold sake is called for.