Sauce:
Sweet vinegar 1 tablespoon
Grated cucumber 1 tablespoon
Polygonum leaves 2 or 3

1. Open each ayu by cutting from the dorsal side. Remove the entrails and rinse well.

2. Wrap each ayu in a dehydration sheet, and place in a refrigerator overnight to remove the excess water.

3. Remove the ayu from the sheets and lightly sprinkle them with salt.Place each ayu between two sheets of bamboo leaves and put each one in its own vacuum-pack cooking bag. Vacuum pack the bags and store in a refrigerator.

4. To serve, open the bag, remove the ayu from the bamboo leaves and broil.

5. Place the ayu on serving dishes. Combine the sweet vinegar, polygonum leaves and grated cucumber, and serve the mixture with the ayu.

Tips:

• When you prepare dried food, the first thing you should pay attention to is to keep the food from decaying. There are several ways to do this, such as : (1) By increasing the concentration of salt, (2) By decreasing the water content, (3) By freezing. However, (1) and (2) can greatly affect the taste of the food, and (3) can damage the protein structure. The second thing you should pay attention to is to prevent oxidation. Freezing is not very well suited for this purpose because it can cause oxidized oil stains. If you use the vacuum-pack cooking method, however, the air is shut out, which can prevent the food from deteriorating. I used kuma-zasa (a kind of bamboo leaves) in this recipe because I heard they have an antibacterial function. I did some research and learned that the chlorophyll and vitamin K in the leaves have that function. I also learned a noteworthy fact that it is especially effective against anaerobic bacteria.
• In this recipe, salt is sprinkled on the fish so as to permeate the fish while being stored in a vacuum-packed bag. Another method is to soak the fish in salted water (18% concentration) for 15 to 20 minutes.