This recipe is based on Nobu's Yellowtail Sashimi with Jalapeños. I don't have access to much Yellowtail but the fresh tuna you can get in the supermarket or fishmongers is more than suitable.
Fresh tuna (say 100g per person for starter sized portions but I usually do more and it usually goes!). Sliced against the grain into 1/2 cm slices.
90ml Yuzu juice
90ml Soy sauce
Fresh jalapeños, sliced finely
Slice your tuna and arrange as artfully on plates as you can be bothered. Mix your yuzu and soy together. Just before serving, pour over the tuna and arrange the sliced jalapeños on top of the tuna. Eat!