
Inspired by Nobu's iconic dish, this recipe brings the elegance of lightly seared tuna with a refreshing tosazu dressing to your home kitchen, perfect for a sophisticated appetizer or light meal.
Prepare the Tosazu Sauce: In a small saucepan, combine the rice vinegar, soy sauce, mirin, dashi (or dashi powder dissolved in water), and sugar. Heat over medium-low heat, stirring until the sugar is fully dissolved. Do not boil. Remove from heat and let it cool completely. You can also refrigerate it to chill.
Prepare the Tuna: Pat the tuna loin very dry with paper towels. Season generously on all sides with salt and freshly ground black pepper.
Sear the Tuna: Heat the vegetable oil in a heavy-bottomed skillet (preferably cast iron) over high heat until it just begins to smoke. Carefully place the tuna loin in the hot pan. Sear each side for about 30-60 seconds, depending on the thickness of the tuna and your desired level of doneness (the center should remain raw). You want a nice brown crust on the outside.
Chill the Tuna: Immediately remove the seared tuna from the pan and transfer it to a plate. For best results and clean slicing, place it in the refrigerator for 5-10 minutes to cool down slightly.
Slice and Serve: Once slightly cooled, use a very sharp knife to slice the tuna against the grain into thin, 1/4-inch thick pieces. Arrange the sliced tuna artfully on a serving platter.
Garnish and Dress: Drizzle a generous amount of the prepared Tosazu sauce over the tuna slices. Garnish with thinly sliced scallions. Serve immediately.