If there is no way to get sugar and flour separately, separating them may be necessary for your recipe. While it may seem difficult, there is a correct way to do it that may be used with a small (half a cup) or large (several cups) amount of the mixture. The process needs to be done carefully and gradually or the flour can turn into dough. Furthermore, it is necessary to have all the right materials to separate the mixture correctly. It's a simple but a timely process that will take a couple of hours to complete.
Fill a plastic container with 2 1/2 cups of water. The water should be lukewarm on the colder side. Having too much water will make it difficult to retrieve the sugar once the process is finished.
Sprinkle 1 tbsp. of the sugar-flour mixture on top of the surface of the water. The sugar should all sink to the bottom of the bowl and the flour should float on top.
Skim the surface of the water with the spoon and take out the flour floating on top. Place the flour in the plastic bowl. Once you have filtered the flour out of your entire mixture, set aside the bowl so water may evaporate off of it.
Pour the sugar-water mixture into a pan. Place the pan on a burner and let it come to a boil. When a sufficient amount of water has evaporated, sugar crystals will develop on the sides of the pan. When the water has completely evaporated, take the pan off the stove and scrape out the sugar crystals.