Rasstegai

Rasstegai (расстегай) is a type of Russian pirog with a hole in the top.

History and etymology
The dish was very popular in Tsarist Russia. In rasstegai the filling is not hidden in dough, and in Russian means "unfastened" pies.

Another version: in Moscow, in the gypsy choir, the beautiful Katya sang very well the Russian song "Sarafanchik-rasstegaychik"; in honor of Katya, rasstegai became very popular meal in taverns in Moscow.

Fillings
The filling usually contains fish, but may also contain meat, liver, rice or mushrooms. The hole of rasstegai is used to add broth to the stuffing.

In literature
The dish is mentioned in Nikolai Gogol's Dead Souls and Vladimir Gilyarovsky's Moscow and the Muscovites.