Cut the potatoes into slices, put on a greased baking sheet, sprinkle with rosemary, drizzle with olive oil and bake at 200 degrees Celsius for 20 minutes, turn again sprinkle with butter, salt, pepper and season with nutmeg and cook for 20 minutes. Squeeze the juice from the lemons. In another pan put salmon steaks, sprinkle with lemon juice. Bake for 30 minutes with the oven. Serve immediately.