For 10 minutes stew one onion with 250g mushrooms (cut mushrooms into slices). Line up two sheets and put a mixture of mushrooms and do so to the end (of 150g buckwheat crust). At the top should be two sheets. Spray them with a little lukewarm water. Bake for 10 minutes at 220 ° C, and then reduce to 180 ° C. If you cannot find buckwheat crust in a smaller package than 500 grams, you can leave half of them to remain in the freezer or refrigerator.