In a large bowl pour the yogurt, eggs, crumbled feta cheese, the oil and noodles and add salt if necessary. Leave little to swell vermicelli. In a greased baking pan spread a crust. Pour it on the swollen noodles and remaining mixture. Spread the other top crust. Sprinkle with 1-2 tbsp sunflower oil and bake in a moderate oven. Serve hot with kefir.