Heat a medium nonstick skillet over medium-high heat. Sprinkle tuna with salt and pepper. Add tuna to pan; cook 1 minute on each side or until desired degree of doneness. Cut tuna into 8 strips and cool.
Shape 1/4 cup rice into a rectangle about the size of 1 tuna strip. Place 1 tuna strip across middle joints of fingers, palm side up. Spread 1/8 teaspoon wasabi over tuna strip; top with shaped rice. Close hand and gently press rice and tuna together.
Wrap 1 nori strip around center of nigiri, ending underneath rice. Repeat with remaining ingredients.