For best results, use high-quality ground meat with a good fat content to ensure flavorful and juicy pelmeni. If the dough becomes too elastic and difficult to work with, allow it to rest for an additional 10-15 minutes. To freeze pelmeni, place the baking sheet with the uncooked pelmeni in the freezer until frozen solid. Transfer the frozen pelmeni to a freezer-safe bag or container for longer storage. Cook directly from frozen, adding a few extra minutes to the cooking time. Experiment with different fillings, such as adding mushrooms or other vegetables to the meat mixture.