Russian cuisine in general is famous for its pies. Not pastries, but pies with stuffings. Traditionally in Russia they baked two variants of pies: oven pies and spun pies.
Onion pie belongs to the first category and was baked in oven, and later on stove. In Russia there has always been an infinite number of stuffings for pies, from salty to sweet, from lean to usual. There were even pies with mixed stuffings, pies in several tiers, pies that had to be eaten only hot, open and closed.
During Lent and Christmas Eve, many different kinds of pies were also served, often with sweet or juicy stuffings. Onion pie is, as the name implies, a pie with a juicy but not sweet stuffing. We are often asked about the propriety of using yeast in cooking historical dishes. At the end of the 19th century you could already buy yeast in a store, at least in cities it did not cause problems. In villages, they cooked it the old-fashioned way, with sourdough.