Cut the chicken breast into bite-sized pieces using kitchen scissors. Place them in a bowl, add sake, salt, and pepper, and massage until the liquid is absorbed. Add potato starch and coat evenly.

Heat salad oil in a frying pan to about 5mm depth over medium heat. Add the chicken and pan-fry, flipping occasionally, until cooked through.

In a separate bowl, mix the sauce ingredients (mayonnaise, ketchup, condensed milk, milk, and lemon juice). Add the cooked chicken and toss to coat.