by Jane and Roger from Penicuik, Scotland
1 cup fish stock
1 cup milk
12 oz white fish
1 bay leaf
1/4 cup capers
2 oz butter
2 oz flour
Pepper and salt
Preheat oven to 180°C. Pour fish stock and milk into a saucepan and bring to a simmer. Add fish, bay leaf, and capers and poach for a few minutes. Remove from heat. Separate fish and liquid, keeping both.
Cook sliced leek in butter until soft. Add flour and stir well. Add liquid from cooking the fish and stir, then raise the temperature and cook for a few minutes until sauce is slightly thickened. Turn off heat, remove bay leaf, and add fish, salt, and pepper. Mash the fish a bit with a fork and set aside.
Cook potatoes and mash them with some milk.
Put fish in the bottom of a baking dish. Cover with a thick layer of mashed potatoes. If desired, season with salt and pepper. Cook for 20-30 min, or until sauce is bubbling beneath the potatoes.