This is a restaurant I got From Chef Chu's Famous Restaurant in Mountain View, California when we lived there. Chef Chu's was one of the best restaurants in the San Francisco Bay area.

Squeeze juice from orange and lemon into a saucepan. Drop in rinds and ginger. Stir in ketchup, sugar, vinegar, water salt and food colorings. Bring to a boil, reduce heat and simmer for 5 minutes. Cool and then remove rinds and pieces of ginger. Note: This recipe makes 1 quart. When ready to use, pour as much sauce as needed into a saucepan. Heat to simmering and add enough cornstarch paste to make the consistency of pancake syrup (it thickens further as it cools).