Pretty basic, but experiment with this.
In a bowl, mix 1/4 cup water 2-1/2 tablespoons rice vinegar 2-1/2 tablespoons sugar 1 tablespoon tomato ketchup (puree is better) 1 teaspoon soy sauce
Then, in a small saucepan, heat the following until they are golden: 1 tablespoon olive oil; 2 teaspoons of crushed garlic; 1 teaspoon of finely chopped ginger
Add in the bowful of the mix you prepared earlier and bring it to the boil, then simmer for a couple of minutes, stirring regularly. While stirring, sprinkle in a teaspoon of cornflower to thicken the mix.
Taste it as you go to ensure the flavours have blended and taste good and add salt or pepper as you wish.