Prepare the Sushi Rice:

• Rinse the Rice: Place the sushi rice in a fine mesh strainer and rinse it under cold water until the water runs clear. This removes excess starch and prevents the rice from being too sticky.
• Cook the Rice: In a rice cooker or a medium saucepan, combine the rinsed rice with 1 ¼ cups water. Cook the rice according to your rice cooker’s instructions or on medium heat, bringing it to a boil and then simmering it covered for 10-12 minutes, until the water is absorbed and the rice is tender.
• Season the Rice: While the rice is cooking, in a small bowl, combine the rice vinegar, sugar, and salt. Stir until the sugar and salt dissolve.
• Cool the Rice: Once the rice is cooked, transfer it to a flat surface like a baking sheet or a large bowl. While the rice is still warm, gently mix in the vinegar seasoning, using a paddle or spoon. Be careful not to mash the rice. Allow it to cool to room temperature.

Prepare the Tuna:

• Slice the Tuna: Using a sharp knife, slice the sushi-grade tuna into thin, even pieces, about ¼-inch thick (roughly 1 cm). The slices should be long enough to cover the top of the rice but not too thick, allowing the texture of the tuna to shine through. Make sure the tuna is very fresh and kept chilled before slicing.

Form the Nigiri:

• Shape the Rice: Wet your hands with water (to prevent the rice from sticking to your hands) and take a small ball of the cooled sushi rice, about the size of a golf ball. Gently press and shape the rice into an oblong mound, making sure it holds together but isn’t too compacted.
• Top with Tuna: Take a slice of tuna and gently place it on top of the rice, pressing it lightly to ensure it adheres to the rice. You can also lightly wet the tuna slice with a bit of soy sauce for added flavor.

Serve:

• Arrange the maguro nigiri sushi on a plate and serve with a small dish of soy sauce for dipping, wasabi on the side, and pickled ginger for cleansing the palate between bites.
• Optional: If desired, a small dab of wasabi can be placed between the rice and the tuna before topping it with the fish.