1. Marinate the chicken: Place the chicken, garlic, soy sauce and sake in a bowl and mix well. Marinade for 15 minutes.
2. Make the spicy mayonnaise: Meanwhile, mix mayonnaise and sriracha sauce together in a bowl and set aside.
3. Season the rice: Add salt to the rice and using a plastic or wooden spoon, fluff the rice (do not over mix or toss) until salt is evenly mixed in.
4. Cook the carrots and ginger: In a small skillet over medium heat, add the oil, carrots, and ginger and stir fry for 2-3 minutes, until vegetables are soft but still yielding a slight crunch. Transfer to a plate and set aside.
5. Cook the chicken: Using the same pan, add chicken and cook on medium for 5 minutes, or until chicken is cooked through. Set aside.

Assembling The Onigiri

1. Mise en place: Set a bowl of water next to your ingredients.
2. Shape the rice: Wet your hands (this prevents the rice from sticking) and grab a small handful of rice. Flatten the rice and shape it into a triangle.
3. Fill the rice ball: Make a dent in the center of the nigiri and spread a little sriracha mayonnaise all the way to the tip of the nigiri. Lay a few strips of scallions, ginger and carrot in the center of the dent. Finish by adding one or two pieces of chicken on top of the vegetables.
4. Wrap the rice ball in nori: Lay the onigiri on top and in the center of a sheet of nori and fold in half.
5. Serve: Divide the onigiri among 2 plates and serve.