Heat a tablespoon of oil in a small pot, add finely chopped onion, garlic and ginger, and grated orange zest. Cook over low heat for about 3 minutes.
Add all the other ingredients: orange juice, orange jam, rice vinegar, soy sauce, sifted starch, and spices (turmeric and cayenne).
Cook, stirring from time to time for a few minutes until the sauce thickens. It should be sweet and sour. If it's too sweet, add a little more vinegar, and if it's too sour - some jam.
It can be served right away or blended until completely smooth (this is what I prefer).