• Dashi konbu (kelp for stock making); a piece 10–12 inches long and 3–4 inches wide when softened
• 4–5 ounces very fresh fillet of fish
• ½ teaspoon salt
• About 1½ cups rice vinegar
• Peel from ¼ lemon or small knob of fresh ginger (about the size of your thumbnail)
• Soy sauce for dipping, optional

If you have a broad piece of kelp left over from stock making, that is perfect. Place it in a pot with a quart of cold water. Bring the water to a boil rapidly, then remove the pot from the heat. Let the kelp sit in the broth until it is cool enough to handle. (Save this broth and use it in lieu of regular dashi stock in other recipes.) If you are using a dried piece of kelp, let it cook for 2 minutes before removing the pot from the heat.

Lay the fish fillet on a flat dish and lightly salt all surfaces. Put the fish aside for 10–15 minutes and you’ll notice a bit of liquid has accumulated. Pat this away gently with paper towels. Cut the fillet in half, lengthwise, slightly on the diagonal. Now lay the two pieces side by side in a small, shallow dish and pour in enough rice vinegar to cover the pieces entirely. Let the fish marinate for at least 30 minutes, but not more than 1 hour, at room temperature.

In the meantime, cut the lemon peel into the thinnest possible slivers. Or peel the ginger and slice it as thin as you can. Pile these slices up, then cut them into very thin threads.

Lift the fish from the rice vinegar, reserving the vinegar for later. Place the fish on a cutting board and, using the sharpest knife you have, cut very thin slices on the diagonal. The outer surfaces of the fish will have already turned opaque from contact with the vinegar; the inner surfaces may still be translucent. Move the slices to a corner of your board and wipe your cutting surface dry before laying down the broad ribbon of kelp. Now arrange the slices of fish on the kelp, leaving a ½-inch border (1). Scatter lemon peel or ginger threads over the fish. Roll the kelp and fish tightly (2) and tie up the roll securely at both ends with string (3). You may find the rolling a bit difficult the first time because of the slippery nature of the kelp. You can always dismantle the roll, wipe the kelp with toweling, and start again. You’ll get the knack of it after one or two tries, I’m sure. Cut the roll in half if necessary to fit it into a wide-mouthed glass or ceramic container just large enough to accommodate the roll or rolls with 1 inch of head space. Pour the reserved rice vinegar over and add more if necessary to cover the roll or rolls completely. Cover your container and marinate for at least 3 hours at room temperature or 8 hours in the refrigerator.

Just before serving, lift the roll or rolls from the marinade. Insert decorative toothpicks evenly spaced about ⅓ inch apart along the roll. Now remove the string. With a very sharp knife, slice between the toothpicks to make bite-size pieces. Serve the rolls chilled or at room temperature, with soy sauce for dipping, if you wish.