You can use regular wheat flour (plain all-purpose flour) to substitute as a thickener in sweet and sour pork. Double the amount that the recipe calls for (if it calls for 1 tablespoon corn flour, measure 2 tablespoons of wheat flour). First spoon the flour into a small cup or bowl, add a little cold water and stir well, then add to the recipe. This should work as a good thickener.