The sugar and flour help the yeast to rise. When the yeast rises, it will expand and have a foamy texture.
If the dough is still sticky, it means that you should continue kneading.
When the dough is double its original size, it means that it has finished rising. If you live in a warm or tropical area, the dough may only need a couple hours to rise. Keep checking on the size of your dough if you are unsure how long you should leave it.
Try to use a cooking oil with a high smoke point that is meant to be used in deep frying. Peanut oil, for example, has a high smoke point, while olive and vegetable oil do not.
If the scrap of dough immediately rises to the top of the oil after you drop it in the pan and does not change size, you will need to keep heating the oil. Check after another five minutes to see whether the oil is ready.
