When it comes to expensive delicacies, one my favourites is sea urchin, or uni in Japanese. If I see it on a menu, I'm almost sure to order it. Because its delicate flavour is so elusive, I like it best raw or, at most, gently heated. Here is an indulgent recipe that lets the sea urchin shine. Ponzu sauce isn't difficult to make, but for this dish, it's fine to use the type that comes in bottles.
Buy well-marbled beef labelled for yakiniku, not the type for shabu-shabu, which is sliced too thin. If you want to be really extravagant, use wagyu beef.
An optional ingredient is wasabi - but only use it if you have the fresh root; the prepared stuff is far too strong. Grate the wasabi just before making the dish, because the flavour fades as it sits.
Shiso leaf is also called beefsteak plant, and the flavour is very distinctive. If you can't find it, substutute Korean sesame leaf.
This is an excellent starter for a dinner party because it takes only a few minutes to cook and assemble. It should be eaten within a few minutes of being prepared, or the heat from the seared beef will make the shiso leaf wilt and the nori sheet soften, instead of being delicately crisp. The amounts listed below make enough for four, serving two pieces per person.
Finely chop the spring onions then put them in a sieve, rinse with cold water and drain. Put the pieces on paper towels and squeeze out the excess moisture.
Pour some ponzu into a bowl large enough to dip the beef slices in. Place a grill pan (preferably well-seasoned cast iron) over a medium-high flame and heat it until it's very hot, coat it very lightly with oil. Dip a piece of beef into the ponzu, then place it in the grill pan and cook it briefly on both sides - you want to sear the exterior but leave the interior as rare as possible. After cooking each piece of beef, lay it on a plate.
Quickly assemble the ingredients: lay the nori slices on a plate and top each one with a shiso leaf. Place the seared beef on the shiso and add a small amount of fresh wasabi, if using. Lay a piece of sea urchin on top then scatter with the spring onion. Sprinkle with shichimi togarashi and a few flakes of sea salt. Serve immediately, with additional ponzu for dipping, if desired.