Anago is conger eel. It is normally served grilled rather than raw, shimmering with a glaze of a tasty sweetened sauce.
To prepare the eel, pin the head down near the fin. At the base of the head, insert the knife in the back only as far as the width of the backbone, and work it through the eel to the tail to open the eel out.
Open up the eel into one whole fillet ad scrape out the entrails. Remove the skeleton by cutting the bone at the base of the head and inserting the knife underneath it, working the knife along to the end of the eel.
Cut off the dorsal and anal fins and rinse thoroughly.
To make the sauce
boil the following:
1 cup dashi stock
1/2 cup soy sauce
1/2 cup mirin
sugar to taste
the prepared eel, with the skin side down into the pot.
Then, cover and simmer for 5 minutes.
Remove the eel and cool before slicing each fillet into 1 1/8 inch (3mm) strips.
Alternatively, you can make the sauce without the eel. Instead, grill the eel and baste it with the sauce.