Geoduck (pronounced “gooey-duck”) is a clam with an oversized siphon (some people call it the neck) that bears an unfortunate resemblance to a certain part of the male anatomy; the siphon and body are so large that the shell can’t close tightly. Geoduck can be expensive at seafood restaurants, but it’s easy enough to prepare at home.
Fresh geoduck is easy to prepare, but if you're squeamish, have the seafood vendor do it for you. The geoduck should be prepared within a couple of hours of being cleaned.
As with other types of fresh shellfish, geoduck gets tough if it's overcooked. For these recipes, the clam is basically raw; it's just blanched briefly, to make it easier to remove the rubbery membrane around the siphon.
Lay several sheets of newspaper on the work surface (this makes it easier to clean up and also helps to absorb some of the liquid). Lay one geoduck on the newspaper with the open side facing right (if you’re right-handed). Run a thin-bladed knife between the lower shell and the flesh, to cut the muscle that attaches the meat to the shell. Turn the clam over and cut the muscle from the other side of the shell. Lay the geoduck on a tray and do the same with the remaining clams.
Prepare a large bowl of iced water. Heat a large pot of salted water. When the water boils, add the shelled geoducks, blanch for 10 seconds, then drain. Immediately put the blanched geoducks in the bowl of iced water and leave for a few minutes, then drain. Lay a geoduck on a cutting board and remove and discard the membrane that surrounds the siphon - it will pull away easily. Cut the siphon from the body. Slice the siphon in half then put the pieces in a bowl. Pull out the mantle (which is long and thin) and place it in the bowl. From the body, cut off and discard the gills, and squeeze out any dark, soft parts, so that all you are left with is the meat. Rinse this briefly to remove any grit then put the cleaned body meat into the bowl.
Mince the garlic. Slice the chillies into thin rounds, removing as many seeds as possible. Put the garlic and chillies into the bowl with the geoduck. Remove some of the leaves from the celery stalks and coriander stems (reserve these for the garnish). Tear the celery stalks and leaves into 3cm (1¼in) pieces (tearing gives more flavour than if you cut it). Roughly chop the coriander stems and add them and the celery pieces to the bowl.
In a small bowl, stir together the soy sauces, rice vinegar and rose (or rice) wine with the sugar until the sugar dissolves. Pour this mixture over the geoduck and other ingredients and mix well. Refrigerate for about 30 minutes (or up to several hours), stirring occasionally.
Spoon the solid ingredients into four starter-portion dishes and drizzle with some of the marinade. Garnish with the reserved celery and coriander leaves, then serve immediately.