It’s not so much a recipe, but a general method:
One part vinegar, one part 100% fruit juice (orange, cherry, mango, pineapple, …). Half a part ketchup to give some body if going in the „fake Chinese direction“ or bag juices / stock from your desired protein for a more classic approach. Sugar to taste (depends on fruit juice, just go by taste), all whipped together and brought to a boil for half a minute or so …
A thickener of choice (flour/butter, cornstarch, …) added and brought to the desired thickness.
