Only sticking with water to make the dough

Many people, including the self-proclaimed Polish Chef on YouTube, use water to bind together their pierogi dough, but water doesn't add much flavor. It's fine if you think of pierogi dough as a vehicle for delicious fillings. However, if you want your dough to be more than a placeholder, consider using milk to make your pierogi. It is important to note that there is a slight trade-off when substituting milk for water. Milk adds richness to the dough, but its fat and proteins can make it slightly sticky. Using water, on the other hand, produces a pliable, easy-to-work-with dough.

Milk also adds sweetness in the form of lactose, making it a better choice for pierogi with a sweet filling. Instead of milk, some pierogi recipes include dairy in the form of sour cream or butter. If you use one of these more solid forms of dairy, you may want to add water to ensure your dough has the proper amount of moisture. Surprisingly, the juice from onions is used as part of the liquid component in a Lithuanian version of pierogi.