First, the onions and peppers are cut into strips and sautéed. The pineapple pieces are briefly seared. Then apple cider vinegar, sugar, salt, ketchup, soy sauce and oil are mixed together and briefly boiled with the fried peppers and onion strips as well as the fried pineapple pieces. When the sauce is boiled, the pineapple juice is mixed with the 4 tablespoons of cornstarch and added to the sauce. Bring to the boil again briefly and set aside. Now the chicken breast fillet is washed and seasoned with salt, pepper and a little soy sauce. Now the batter is made. To do this, flour, cornstarch, baking powder, oil and water are mixed together to form a smooth dough. The chicken breast fillets are placed one after the other in the batter until they are completely coated. (It is best to use a separate container for each fillet.)