Cut 300 g boneless chicken thigh into bite size pieces. (40-50g, 1.4-1.7 oz per piece)
In a zip lock bag or tupperware, add 1 tbsp Japanese soy sauce (koikuchi shoyu), 1 tbsp sake, ¼ tsp ground black pepper, 2 tsp grated garlic and 1 tsp grated ginger root together with the chicken pieces and marinate for 30 mins in the refrigerator.Once marinated, start preheating a pan of oil to 160 °C °C (320 °F). It should be about 3cm deep (just over 1 inch).
Sprinkle about 5 tbsp potato starch (katakuriko) onto a plate. Shake the excess marinade off each chicken piece before rolling it in the starch.
Once the oil is hot, place the chicken pieces in the pan and shallow fry at 160 °C (320 °F) for 3 minutes on each side.
Turn up the heat to 190 °C (374 °F) and fry for 1 minute on each side.
Transfer the chicken to a wire rack or absorbent kitchen towels to allow the excess oil to drip off.
Serve and enjoy.
Notes
Store leftovers in the fridge for 1-2 days or in the freezer for up to 1 month. Reheat in the microwave or crisp it up in the oven/grill.