I don’t know what its secret is, but my grandmother used potato water (boil potatoes & reserve the liquid) & sometimes even added mashed potatoes to her dough. It made a smoother dough……..but then again, my grandmother was a wonderful cook. But, to answer your question, using plain water will work as well, as long it is warm to help the yeast grow. You may have to experiment & get back to us on that one! Good luck!