Step 1

Rinse the rice in cold running water a few times, until the water runs clear.

Step 2

Place the rice and the water in a pot, with a pinch of salt, cover and bring to a simmer.  Reduce the heat to the lowest setting, and continue to cook for 10 minutes.

Step 3

While the rice is cooking, mix the rice vinegar, sugar and salt, and heat gently until the sugar dissolves.

Step 4

Once the rice is ready, let cool slightly, and then transfer into a plastic or wooden bowl.  Pour the seasoned vinegar over the rice, and using a wooden spoon, mix it in lightly (don't use metal utensils or bowl, as it will react with the vinegar).

Step 5

In a deep bowl whisk all marinade ingredients, including the green onions and toasted sesame seeds.

Step 6

Using a sharp knife, cut the tuna into 1/4" thick cubes, and add to the bowl with the marinade. Stir well.

Step 7

Chop the avocado, cucumber, radishes and whatever other veggies you like.  Divide the rice into two bowls.  Add the tuna, and chopped veggies, and top with more sesame seeds, sprouts, or other toppings of choice.  Serve with soy sauce, or hot sauce on the side.