Cut pineapples into small pieces. Slice ginger root and carrot.
In a sauce pan combine water, vinegar, sugar and tomato ketchup.
Add ginger and carrot slices and bring to a boil. Cook slowly for five minutes.
Dissolve cornstarch in a small amount of water and add to the sauce. Stir until thickened, then add pineapple pieces to sauce.
To Serve: Pour sauce over your choice of meat, poultry or fish and serve.