Traditional Swedish Jansson's Temptation

Method

1. Preheat oven to 200°C (390°F).
2. Peel and slice potatoes into thin rounds.
3. In a pan, melt butter and sauté onion until translucent.
4. Mix cream of mushroom soup with a little water to thin it.
5. Layer potatoes and herring in a baking dish.
6. Pour the soup mixture over the layers.
7. Sprinkle cheese on top and bake for 25-30 minutes.