Slice the lemon, onion, and red bell pepper. Trim the roots of kaiware sprouts.

Pierce the chicken thigh with a fork and season with salt and pepper.

Place the chicken in a microwave-safe dish, sprinkle with sake, cover loosely with plastic wrap, and microwave at 600W for 6–7 minutes. Let it cool with the wrap on, then cut into bite-sized pieces. Reserve 2 tbsp of the steaming liquid.

In a bowl, mix the marinade ingredients with the reserved steaming liquid. Add the onion and red bell pepper, and mix well.