Make these for your next party as an appetizer. Piroshki are a very popular pastry here in Greece, probably brought over with the return of the Greeks from 'Pontos', now a part of Russia. Here, they are traditionally fried, but I find them much too rich (although very good) that way. This version is baked, and does not suffer any (just less calories) for it. I have given 3 different filling recipes. One for meat, one potato, and one mushroom. They are all great and each recipe will yield enough filling for 20-22 pastries. The prep time approximate - the pastry does need two hours to 'rest'.