At work, my lunchtimes are regularly spent gossiping with friends over a pub baked potato. There is nothing wrong with baked potatoes; indeed, a baked potato can be a thing of wonder (something I hope to demonstrate in the coming weeks). The pub baked potato, however, is a sad, microwaved thing, whose cheese has been melted under heat-lamps as it waits to be served. More often than not, this means that the salad which has been shoved on the side of the plate is melting too.
Salads shouldn’t melt.
So. It’s time to rehabilitate the potato.
I love gratins; especially at this time of the year, when it’s getting cold, there is nothing nicer than lovely, starchy potato which has absorbed its own weight in scented milk and cream. You can make a whole meal of a gratin by adding extras – I had some smoked mackerel from Spinks in the fridge. A mackerel gratin is just the thing to start me feeling good about potatoes again.
I start out by infusing 240ml of milk with some thyme, a bay leaf and some parsley from the garden. This is a great application for the woody flowering tops of the parsley I can’t use to garnish (and which I should remove to make the leafy part of the plant more bushy). They’re very fragrant, and are perfect for this. I also add some celery leaves from the centre of a bundle in the fridge, a crushed clove of garlic, a clove, three peppercorns, a quartered shallot and some salt. The milk comes to a simmer and is taken off the heat while I slice the potatoes.
It’s important to slice the potatoes very thin. I wish I had a mandoline – a device to slice vegetables very evenly, and very thin. I make a mental note to go to the kitchen shop soon.
Slicing the potatoes thinly increases the surface area that’ll be exposed to the wet ingredients, and so increases the starchyness of your finished gratin (your sauce will be thicker); it’ll also result in a crisper finish. I layer them in a thick-bottomed, enamel dish, which has been buttered to within an inch of its life. One fillet of smoked mackerel goes on top of this, flaked, and then a final layer of potato goes on top.
I strain the infused milk through a sieve, then add 350ml of double cream to the herbs and spices that are left in the sieve, and simmer that on the stove too. The potatoes, fish and fragrant milk are covered with tin foil and put in an oven preheated to 220c. (Yes, I know I have sloshed milk all over the counter. And everything looks strangely glaucous because the light in my kitchen is atrocious and I have to use the flash.)
The house begins to smell very, very good.
Once the cream has come to a simmer, I remove it from the heat, and strain it into a jug with a tablespoon of grainy Dijon mustard. Twenty minutes later, most of the milk has been absorbed into the potatoes. I pour over the cream, sprinkle a little finely grated parmesan over the top, dot with butter and return the dish to the oven, without the tin foil. (I love my Microplane grater; I spent years sweating over grating solid chunks of parmesan, but I got a Microplane after I saw one being used in an Italian restaurant and asked what it was. It also does a beautiful job of pulping garlic and ginger.) I’m careful not to add too much parmesan; it’s there to flavour, not smother.
The gratin sits in the oven for another 25 minutes. When it comes out it is crisp and golden, and the creamy sauce is bubbling gently between the slices; the underside is golden too, and there is a soft, smoky layer of unctuous, creamy potato and mackerel in the middle.
This is how autumn food is meant to be.
Thankfully, I do not own a heat lamp, so the (bagged) salad is crisp and does not go wet and stinky on me.
Those particularly interested in the lore of the gratin, and the reasons for the wonderful, lactic taste that all of this messing around with potatoes and cream produces, should go directly to Amazon and buy everything Jeffrey Steingarten has ever written. This will not only inform you in wonderful, systematising detail about the miracle that occurs in your gratin dish, but will keep you implausibly happy in the bath for as long as it takes you to read it all, and then for the half hour (turn the hot tap on at this point; things will be getting a little clammy) it takes you to bemoan the fact that there isn’t a third volume.