Sweet & Sour Sauce

1 1/2 t potato flour
4 T water
4 T pineapple juice
3 T rice vinegar
4 T sugar
1/4 t salt
2 t soy sauce
2 T tomato ketchup
1 1/2 t Worcestershire sauce
1/2 C diced pineapple

Mix all ingredients and bring to a soft boil, stirring constantly.