Mix all ingredients for the nanban sauce and set aside.
For the tartar sauce, sprinkle the chopped onions with salt to make them lose water. Then rinse with water and dry well with a paper towel. Dice the egg and add to the mayonnaise with onions, pickles and milk. Season to taste with salt and pepper.
Remove the fat from the meat and then cut into bite-sized pieces of the same size. Marinate with sake, salt and pepper for a few minutes, then roll in the flour.
Tip: It is best to put the flour and meat in a sealable freezer bag, then close and shake well. So the flour is evenly distributed on the meat instead of in the kitchen.
Then turn in egg.
Heat the oil in a pan and fry the meat until golden brown. Dab the finished meat with a paper towel and turn in the nanban sauce.
Serve nanban chicken with tartar sauce and possibly a small side salad.