These are dumplings (pronounced oosh-ka) and a translation of the name is 'little ears'. They can be filled with mushrooms and cabbage or minced pork and a good way to serve them is with barszcz czerwony. This is how they are traditionally eaten during Christmas eve.
I ate uszka only once and I just bought some frozen uszka from the sklep (shop) and put them in boiling water with oil for a small time. It is important to keep checking frozen dumplings when heating as overcooking destroys the pastry. When they are soft add unstrained barszcz and serve.
I tried the mushroom uszka and I must say they were not my favourite dumplings but I have been told that I have to try them fresh and so I will update this when I do.