The traditional Bulgarian cheese made from sheep's milk is called "sirene." It is a white, brine cheese that has a tangy and slightly salty flavor. Sirene has been a staple in Bulgarian cuisine for centuries and is commonly used in dishes such as banitsa (a pastry filled with cheese), shopska salad (a salad made with tomatoes, cucumbers, onions, and sirene), and grilled cheese sandwiches. It is made by curdling fresh sheep's milk with rennet and then draining and pressing the curds into molds. Sirene can be aged for up to a year, which intensifies its flavor and texture.