Flour dusted on the counter becomes part of the dough and throws off its proportions; dough with too much flour becomes firm and dries out when baked. Starch does not cause this problem because it contains no gluten and does not bind to the dough. Starch is preferred for dough rolled out over a long time, such as yufka, baklava, and manti; a small amount of flour is enough for quick rolling.
Flour dusted on the counter does not stay there; as the dough is rolled out, it sticks to the surface and gets mixed in. During a long rolling process, the amount grows surprisingly large, and the ratio of flour to water in the dough changes without you realizing it. The result is dough that starts out soft, gradually becomes firm, and comes out dry after baking. The same problem occurs when kneading on the counter and often goes unnoticed. That is why the amount sprinkled on the counter is not included separately when the recipe’s flour is weighed; it is added on top.
Starch breaks this chain. Because it contains no gluten, it does not bind to the dough and instead remains as a thin separating layer on the surface. It does the same separating job with much less and barely changes the dough’s proportions. Cornstarch is the most common choice; wheat starch and rice flour work the same way. Its flavor is neutral, and its presence is not noticeable after baking. Starch also creates a more slippery surface, so the dough turns more easily on the counter and rolling goes faster.
The choice depends on how long the dough will be rolled. A small amount of flour is enough for dough rolled out quickly in one go, such as pizza and cookies, and its effect is limited. For long, folded, stacked doughs such as yufka, baklava, manti, and hand-rolled borek, starch is clearly superior. Sprinkling starch between the layers also keeps them from sticking together. Starch is considered essential for baklava dough; layers made with flour stick together while baking and do not separate.
Whichever powder you use, the amount is small. Dust the counter with a thin layer, refreshing it with a little more if needed each time you turn the dough. A pile of flour or starch leaves dry spots on the dough’s surface, which show up as white marks after baking. Always shake off the excess; especially with folded dough, too much powder keeps the layers from bonding and the structure falls apart. Dusting with a fine-hole shaker or a sieve instead of your hand spreads it much more evenly.
There are two other options besides flour and starch. Some doughs, especially wet ones, are rolled out with a thin layer of oil instead of powder; oil the counter and rolling pin, and the dough spreads without slipping. The second option is rolling the dough between two sheets of parchment paper; this method uses no powder at all and works especially well for soft doughs such as cookie dough. Dough rolled between parchment can also be transferred directly to a baking sheet. It can also be placed directly in the refrigerator between the sheets of parchment, rested there, and cut afterward.