The potatoes can be assembled ahead, covered and refrigerated until ready to use. To serve, place on a baking tray and reheat in a moderate oven until the filling is hot then place under a hot grill to brown the tops.
4 large floury potatoes (such as Agria), about 300 grams each
300 grams smoked fish
200 grams peeled raw prawns
1 cup milk
1 clove garlic, crushed
1 tablespoon wholegrain mustard
½ cup sour cream
¼ cup chopped flat-leaf parsley
sea salt and freshly ground pepper
knob of butter
½ cup freshly grated Parmesan cheese
Preheat the oven to 200˚C.
Potatoes: Wash and dry the potatoes and prick with a fork. Rub with olive oil and sprinkle with sea salt then place on a baking tray. Bake for 1 hour or until the potatoes are soft when pierced with a skewer. Remove from the oven and preheat the grill.
Filling: Flake the smoked fish into large bite-sized pieces, discarding the skin and bones. Place in a sauté pan with the prawns, milk and garlic, season and simmer gently for 5 minutes or until the prawns are just cooked. Strain the milk into a jug, reserving the fish and prawns.
Holding each hot potato in a tea-towel, cut off the top and scoop the flesh into a bowl. Add the mustard and sour cream and beat in enough hot poaching milk to make a creamy mash. Season and fold in the parsley, prawns and the smoked fish.
Put the potato skins back on the baking tray and spoon in the filling, piling it up above the shell. Dot the tops with butter and scatter with Parmesan and freshly ground pepper. Place on the middle shelf of the oven and grill until the tops are golden and the filling is hot. Serve with a crisp green salad.