Pirogues is a Russian pastry very similar to English Cornish pasty. The difference is that pirogues is yeast dough-based and lighter than the puff pastry.
Sourdough bread is healthy, and bread baked in this way has a good effect on digestion. Sourdough bread also provides good microbes for the intestine
Sourdough starter is natural yeast you make at home. Once you have made a starter you can have it for an eternity, as long as you take care of it.