From my dear friend, BJGourmet:
"Ever wondered how the Chinese restaurants make their delicious red Sweet & Sour Sauce? And the little jars from the grocery store don't stretch as far as you'd like?
I learned their secret many years ago, and would like to share it with all of you. Enjoy!!
BJ's Chinese Sweet & Sour Sauce
1/4 of a fresh lime
1/4 of a fresh lemon
1/2 of a fresh orange
2 tbsp vegetable oil
4 cups water
2 tbsp crushed fresh garlic
2 tbsp minced fresh ginger
Liquid red food coloring
1/2 tsp salt
2 cups sugar
1 cup white vinegar
1/4 cup cold water
2 tbsp cornstarch
Remove and save the peel from the fruit. Squeeze the juice from the pulp and set aside (discard the pulp). Cut the peels into fine julienne.
Preheat the vegeable oil in a heavy saucepan over medium-high heat. Add the julienned peel and stir until golden in color. Add all the water at once, plus the garlic and ginger and boil 5 minutes.
Add the reserved fruit juice. Remove from heat and pour through a wire-mesh strainer to remove all solids. Stir in enough of the red food coloring until it's the authentic reddish-orange color. Then add the salt, sugar and vinegar; stirring over medium heat until the sugar is dissolved.
You now have your syrup concentrate; allow it to cool and store refrigerated in a glass or plastic container. Trust me; it'll keep for months.
When ready to serve, pour about half the syrup concentrate into a heavy saucepan; heat it to boiling.
Prepare a slurry with the 1/4 cup water and 2 tbsp cornstarch. Whisk in a SMALL amount of the slurry at a time until you've got the consistency you desire and the sauce is clear and glossy.
NOTE: Adding the slurry in small amounts is important because the high sugar content of the syrup will cause it to thicken quickly...