I can also add buckwheat roasted with muchrooms, and russian-style roasted potatoe with mushrooms.
And why nobody menshioned jelled meat (cold meat in stark boullion served with spicy horseradish)? Also cold jelled fish is popular.
And traditional Soviet food for new year holidays - Olivie salad (small pieces of meat, boiled potatoes, green peas, marinaded cucumbers, boiled eggs served with mayonase).