Cup of Yum
1. Before You Start: Prepare your sushi rice ahead of time. For instructions, see my step-by-step guide on How to Make Sushi Rice. For this recipe, you‘ll need 1½ cups sushi rice (cooked and seasoned) as each roll requires ¾ US cup (110 g) of sushi rice. ¾ cup uncooked Japanese short-grain rice is 1 rice cooker cup (150 g, 5.3 oz), which yields roughly 2¼ cups (330 g) of cooked rice. Important: Cover the sushi rice with a damp cloth at all times to prevent it from drying.
2. Gather all the ingredients.
3. Make the vinegared water for dipping your fingers (tezu) by combining ¼ cup water and 2 tsp rice vinegar (unseasoned) in a small bowl. Tip: Dipping your fingers prevents rice from sticking to them.
4. Cut 4 oz sashimi-grade tuna into ¼-inch (0.5-cm) cubes; alternatively, you can mince the tuna.
5. In a medium bowl, combine the tuna, 3 tsp sriracha sauce, ½ tsp toasted sesame oil, and most of the sliced 2 green onions/scallions (set aside some for topping each roll).

To Roll the Sushi

1. Cut your 1 sheet nori (dried laver seaweed) in half crosswise. Lay a half nori sheet, shiny side down, on a bamboo sushi mat covered with a layer of plastic film. Wet your fingers in the tezu and spread ¾ cup (110 g) sushi rice evenly onto the nori sheet. Sprinkle the rice with 1 Tbsp of the total 2 Tbsp toasted white sesame seeds called for in this recipe.
2. Turn the sheet of nori over so that the rice side is facing down against the plastic wrap. Line the edge of the nori sheet at the bottom end of the bamboo mat. Place half of the tuna mixture (if you‘re making 2 rolls) in a thin row along the bottom end of the nori sheet.
3. Grab the bottom edge of the bamboo mat while keeping the fillings in place with your fingers and roll into a tight cylinder. Lift the edge of the bamboo mat and continue to roll it forward while keeping gentle pressure on the mat. Repeat with the rest of the ingredients.

To Serve

1. With a very sharp knife, cut the Spicy Tuna Roll in half and then cut each half into 3 pieces. Clean the knife with a damp cloth every few cuts. When you cut sushi rolls, dip your fingers in tezu or cover the roll with plastic, so the rice won‘t stick to your hands.
2. Put a dollop of Homemade Spicy Mayo on top of each sushi piece and garnish with the remaining green onion.

To Store

1. It‘s best to enjoy sushi rolls on the same day. Rice gets hard and dry in the refrigerator. Therefore, if you really want to keep sushi rolls in the refrigerator, my recommendation is to cover them with plastic and a thick kitchen towel, so the rice will stay cool and safe, but not become too cold.