Seasoning mix:
3 tablespoons sake (boil down before use)
2 tablespoons mirin (boil down before use)
15g sugar
2 2/3 tablespoons light-colored soy sauce
Ginger root

1. Cut the conger eel open and remove the head, fins and bones. Place on a cutting board with the skin side up, pour boiling water over it and then soak in ice cold water. After it cools down, scrape the sliminess off the skin with a knife. Rinse again, and dry.

2. Combine the ingredients for the seasoning mix in a pan, bring to a boil and allow to cool.

3. Put the conger eel, sliced ginger root and 2 tablespoons of the seasoning mix in a vacuum-pack cooking bag, and vacuum pack it to 100%.

4. Cook in a steam oven at 92Ei for 20 minutes. (If you want to store it, rapidly cool it to 3Ei within 90 minutes and store in a thermostatic refrigerator at 0 to 3Ei. To reheat, heat at 90Ei for approx. 5 minutes.

5. Remove the eel from the bag and place it with the skin side up over a spread wet, squeeze-dried cotton cloth. Mount the sushi rice on the eel in a stick-shape. Roll the eel and rice together using the cloth and adjust the form.

6. Place the sushi on a griddle and grill the surface of the fish. Cut into pieces on a cutting board.

7. Serve on a plate and apply the boiled down seasoning mix over the eel and top with pepper leaf-buds. Garnish with some ginger root briefly marinated in vinegar.

Tips:

• Please note the cooking temperature and time for the conger eel. Cooking fish at over 90Ei for as long as 20 minutes seems to conflict with the general theory of vacuum-packed, low-temperature cooking. However, the conger eels' skin is so thick that it turns out tough if the general cooking method is applied, as it takes into account only the time and temperature to coagulation of the protein. This is because hydrolysis of the colagen contained in the skin cannot be completed and the colagen remains hard instead of being gelatinized when cooked at low temperatures or for short amounts of time. Therefore, conger eels need to be cooked longer at higher temperatures.
• When employing the vacuum-pack cooking method, pay special attention to sanitation and make sure your hands and cooking utensils are properly disinfected.