Cut the chicken breast into bite-sized pieces, about 1 cm thick. Place them in a plastic bag with grated ginger, sake, and soy sauce. Massage the bag to coat the chicken and let it marinate for about 10 minutes.

Prepare the vegetables: cut the bamboo shoot into bite-sized pieces and boil it, then drain. Cut the green bell pepper into chunks, slice the carrot into 5mm thick half-moons, and cut the onion into 3cm wide wedges, then separate them.

In a bowl, mix the sweet and sour sauce ingredients: vinegar, soy sauce, sugar, potato starch, and water. Set aside.

Coat the marinated chicken pieces with potato starch. Heat 4–5 tbsp of vegetable oil in a frying pan over medium heat and fry the chicken until golden brown. Remove and set aside.

Wipe the frying pan with a paper towel and heat 1/2 tbsp of vegetable oil over medium heat. Stir-fry the carrot first, then add the green bell pepper, onion, and bamboo shoot. Cook until the onion becomes translucent.