What’s cooking today: Fish pie au gratin

This recipe is inspired by reader Heather Davies’ fish pie, which she sent to me this week after reading our Throwback Thursday cottage pie feature last week. I have not followed her recipe precisely, but I did take a few things from it, and married them with my memories of my dad’s “fish au gratin”, as he always called it, and my mom’s passion for mashed potato. So, a bit of a mash-up then.

Heather Davies uses Cape salmon, yellowtail, kingklip or kabeljou, none of which is all that common in my part of the Karoo. But in my small town, finding anything other than frozen hake is a minor miracle, so when I encountered a pack of butterfish I grabbed it before anyone else could get their grubby paws on it. And butterfish is superbly sturdy and pleasing for a fish pie. 

The best tip I gleaned from Heather’s recipe was to use the poaching milk for the fish, once it’s cooked, to double up to make a quick béchamel sauce. Genius. She also shared that she likes to use a little allspice in a béchamel. I did, as well as tarragon, and I concur. In fact, I find myself using more and more allspice these days, a spice I had long ignored.

If you want to follow Heather’s recipe more closely, add these two steps to the dish I describe below: boil 3 or 4 eggs, halve them and lay them out on the cooked fish before pouring the sauce over, then top with mashed potato and layer the mash with sliced tomatoes (she prefers to remove their skins) before grating cheese over or just dotting the mash with butter. It sounds marvellous, but I wanted to bring in some of my dad’s way with gratinated onions and cheese.

This isn’t the sort of recipe that needs exact measurements. Start by choosing the right oven dish to fit the fish fillets you have, and assess how many potatoes you’ll need to peel to cover it with mash. The same applies to poaching the fish. As much full cream milk as it takes just to cover them, in a pan that fits the fillets side by side, is how much milk you will need.

(Serves 4)

Ingredients

Fillets of firm white fish, enough for 4 servings

1 large onion, sliced

Milk, enough to cover the fish in a pan

Potatoes, peeled, enough to make mash to cover the fish in your chosen dish

4 or 5 small sprigs of fresh tarragon or 1 heaped tsp dried

Generous pinch of ground allspice

Salt and pepper to taste

Butter for greasing the dish, more for frying the onions, and yet more to whisk into the mashed potatoes

2 heaped Tbsp (yes, more) butter for the béchamel

2 Tbsp flour

Cheddar cheese, grated, as much as you fancy

Method

Peel and boil the potatoes in plenty of well salted water. Drain and mash, then whisk in a hefty knob of butter and a little milk (though Heather prefers not to add milk as it might make the mash too soft). Adjust seasoning with salt and white pepper (preferably) after tasting if you like.

Grease a pan big enough to fit your fish fillets and pour milk over to cover. Add a few sprigs of tarragon, or some dried tarragon, and a generous pinch of allspice. Season with a little salt and pepper (I used white). Bring the milk to a gentle simmer (keep an eye on it to make sure it doesn’t overheat and boil over) and cook gently until the fillets are quite tender, about 10 minutes. They will cook more in the oven.

Caramelise the sliced onion in a little butter until golden.

Grease your oven dish. Lay out the cooked fish.

In a saucepan, melt 2 Tbsp butter on a low heat, then remove from the heat and whisk in 2 Tbsp flour. Return to a low heat and pour the hot poaching milk in a little at a time, whisking, until it is all incorporated. Stir over a low heat until it thickens.

Pour the béchamel over the fish, top with mashed potatoes, then the caramelised onion, and grate plenty of Cheddar over.

Bake in a 200℃ oven until golden. It really doesn’t need a side dish. DM/TGIFood

To enquire about Tony Jackman’s book, foodSTUFF (Human & Rousseau) please email him at [email protected]

Our Thank God It’s Food newsletter is sent to subscribers every Friday at 6pm, and published on the TGIFood platform on Daily Maverick. It’s all about great reads on the themes of food and life. Subscribe here.