500g centre-cut bluefin tuna (preferably with a piece of the belly flap intact)
1tsp black sesame seeds, toasted
Sea salt, to taste
2tbs shiro dashi (white soy that has been fermented with dashi)
1/2tsp grapeseed oil
2tbs chives, finely sliced
1 shiso leaf, finely chopped at the last minute
1 yuzu or Japanese citron (we substitute Meyer lemon in California)
For garnish 6 shiso leaves (perilla)
Maldon salt or a granular Japanese sea salt
Place the tuna on a very clean surface. Place a non-reactive metal bowl on ice at the ready. With a sharp knife, remove the tuna skin. Using a teaspoon, gently scrape the tuna flesh off the skin and remove the sinew. This takes patience and a gentle hand. You do not want any sinew or foreign matter in the tuna. You do not want to bruise the flesh, but you do want to maintain the fat in the flesh as you work. Place the flesh in the iced bowl as you work. Some parts of the tuna will be fattier than others. If you work carefully you will have a purée of the tuna with a beautiful texture. Carefully fold it together so it is homogenous.
Season the tuna at the last moment with the sesame seeds, salt, shiro dashi, grapeseed oil and chives, by folding everything in with a spoon. Add the chopped shiso to taste. Add some fresh yuzu juice and just-grated peel to taste. It is important that you get just a hint of the yuzu in the tartare and not a dominating flavour.
Shape the tuna into quenelles with two spoons and place on a shiso leaf. Garnish with Maldon salt or equivalent and serve immediately.