Natto gratin

Cut the Nagaimo into cubes with the skin on, deep fry and drain the oil

Mix the yam and natto in a bowl, then add the natto sauce and Happomibijin halfway through. Add the chopped green onions and mix quickly

Put commercially available white sauce and prepared soy milk in a frying pan and heat until it becomes a thin sauce

Place aluminum foil in a baking tray and lightly coat it with butter. Spread [2] on the baking tray and pour the white sauce [3] on top

Place the sliced ​​cheese on top and place in the toaster oven. Bake for about 5 minutes, then remove and brush with egg yolk before placing back in the toaster oven

After baking for about 3 minutes, brush with egg yolk again, bake for another 3 minutes, then remove from the oven. Serve on a plate and it's done