To prepare Finnan haddie, begin by cutting off the fins from the fish. If the fish is large, cut it into serving pieces. Next, place the fish in a skillet or large saucepan and barely cover it with milk or a mixture of milk and water. Sprinkle pepper over the fish and simmer gently for 10 to 15 minutes, or until the fish is tender. Once cooked, the Finnan haddie can be served topped with a poached egg for a delicious and classic breakfast dish.