Pelmeni are traditional Siberian food and is, of course spread throughout the whole what used to be soviet union. It is said that it's origin is Chinese won tons.
No matter what the origin is it it tremendously popular. It is made with pork, beef, lamb or chicken, or any variations of the above. It is made with a raw meat, unlike pirogi. And as was mentioned no sweet or cheese fillings.
It is usually served with sour cream, vinegar, or I suppose anything you like.
You are what you eat.