Sauerkraut and mushrooms are the perfect marriage in polish pierogi, polish naleniki (also known as blintzes or crepes), and polish uszka (known as "Little ears"), lithuanian koldunai, and kulebiak. Since these are meatless-if using vegetable broth instead of chicken broth-they would be perfect for lenten meals or for wigilia, also known as christmas eve supper, and fit for an ovo-lacto vegetarian. If you have any leftover filling, it freezes well.