Heat the oil to 190C/375F. Cook the dough circles one or two at a time for three minutes on each side, until deep doughnut brown. (If you are cooking whole croissants, nine minutes each side at 160C/320F will do the trick.) Lift out and drop in the rose-scented sugar, turning until well coated. Put to one side and repeat with the rest of the circles. (You can then fry the trimmings in the same way, or bake them and use to make a croissant and butter pudding, replacing the bread, and most of the butter, with the croissant.)