Japanese Onigiri Lunch Boxes: Make-Ahead Salmon and Tuna Mayo Rice Balls for School

Rinse the rice in cold water, swirling and draining 4 to 5 times until the water runs almost clear. Cook with 3 1/4 cups water in a rice cooker or covered pot, then rest 10 minutes.

Serves 4

Ingredients

• 3 cups uncooked Japanese short-grain rice
• 3 1/4 cups water
• 1 salmon fillet (about 6 oz), skin on
• 1 can (5 oz) tuna in oil, well drained
• 2 tablespoons Kewpie or regular mayonnaise
• 1 teaspoon soy sauce
• 1 1/2 teaspoons fine salt, divided
• 4 sheets nori, cut into 3 strips each
• 1 tablespoon toasted sesame seeds
• 1 small cucumber, sliced, for the lunch box
• 4 tamagoyaki slices or hard-boiled eggs, for the lunch box

Instructions

1. Rinse the rice in cold water, swirling and draining 4 to 5 times until the water runs almost clear. Cook with 3 1/4 cups water in a rice cooker or covered pot, then rest 10 minutes.
2. Meanwhile season the salmon with 1/2 teaspoon salt and broil or pan-sear 4 minutes per side until cooked through. Cool, discard the skin, and flake into small pieces.
3. In a small bowl, mix the drained tuna with mayonnaise and soy sauce until creamy.
4. Transfer the hot rice to a wide bowl and let it cool just until you can handle it, about 5 minutes. Stir in the sesame seeds.
5. Wet your hands with water, then rub a pinch of the remaining salt across your palms. Take about 1/2 cup of rice and flatten it slightly in your palm.
6. Press a heaping teaspoon of salmon or tuna mayo into the center, fold the rice over the filling, and squeeze gently into a triangle with three firm presses, rotating as you go.
7. Repeat with the remaining rice and fillings to make about 12 onigiri, re-wetting and re-salting your hands each time.
8. For lunch boxes, wrap each onigiri tightly in plastic wrap and pack the nori strips separately so they stay crisp; kids wrap the nori around just before eating. Add cucumber and egg on the side.
9. Onigiri keep 1 day at cool room temperature in an insulated lunch bag; refrigeration hardens the rice, so make them the night before and store in a cool spot, or freeze and thaw overnight.
10. Onigiri have filled Japanese bento boxes for centuries, and today every konbini sells dozens of varieties. Salmon (shake) and tuna mayo are consistently the two best-selling fillings in Japan, and the rice ball's portability, salt-cured keeping quality, and friendly shape make it the country's quintessential school and picnic lunch.

Nutrition (estimated, per serving)

• Calories: 510 kcal
• Protein: 24g
• Fat: 13g
• Carbohydrates: 72g
• Fiber: 2g
• Sugar: 1g
• Sodium: 940mg