Chicken fillets with sour sauce

Beat the egg white until foamy, add the sugar and ground ginger and place the chicken breast fillets in the mixture. Leave for at least 10 minutes. Meanwhile sauté the leeks in a little oil until glossy, add a little water and boil until soft. Remove from the pan and set aside. Season the chicken breast fillets with salt to taste and roll in cake flour. Fry in a little heated oil until brown and cooked but not dried out.
Mix the remaining ingredients together and heat slowly while stirring continuously. Heat until the sauce thickens slightly and season with a little salt. Serve the chicken with the leeks and sour sauce.
Serves 3-4.