Jacket potatoes are the ultimate winter convenience food – my modest circle of friends includes a lady who was sent to school with one wrapped in foil as a hand-warmer-cum-packed-lunch and a triathlete who eschews the pre-race energy bars and powders beloved of his fellow competitors in favour of a simple spud; easier to open, apparently. They're popular with everyone from hearty outdoors types who can knock up a campfire in less time than it takes me to strike a match, to Saturday shoppers – the jacket potato cart, often mystifyingly Victorian-themed, being a fixture of many town centres on a Saturday afternoon.
This weekend, up and down the country, thousands of Britons will be grimly chewing their way through charred remains in the name of Guy Fawkes, who seems, as if annual immolation wasn't punishment enough, to have become the unofficial patron saint of the burnt potato. Although I wouldn't dream of depriving anyone of the fun of poking around in some ash for that elusive final spud, ovens were invented for a good reason: jacket potatoes.
The clue to the perfect jacket potato lies in the name – any old baked potato can have a delectably fluffy interior, but it takes real skill to achieve that wonderfully crunchy skin. It's not something which can be rushed, which is presumably why most high-street potatoes are such damp squibs: this is a treat best cooked at home. A note of caution, however, from the ever-wise Nigel Slater: "A good baked spud is as much about luck as good planning," he warns. "You can follow all the rules and yet food sometimes does its own thing … Sometimes cooks just have to cross their fingers." True enough – but you can at least improve your chances by getting the rules right to start with.
Plain and simple
There is at least no debate about the best kind of potato for baking – that billowing, cloud-like flesh is the exclusive preserve of the floury varieties, such as Maris Piper or King Edward. Some people, including Nell McAndrew, reckon that's the only thing you need for a baked potato – so I give it a whirl. My floury potato goes into a 190C oven for 50 minutes, until it gives slightly when I press it with my asbestos fingers. It's a bit of a disappointment though; although the inside is fluffy enough, so is the skin, which reminds me powerfully of a Russet apple. That's the last cooking advice I'm taking from a glamour model.
Salt and water
Nigel Slater also keeps things nice and simple. He suggests washing the potato (which might be a practical necessity, depending on where you buy yours) and then dusting them with sea salt while they're still wet, which gives a 'crisp and savoury skin'. He's right – it's got a definite crunch to it, and, ready seasoned, only requires a knob of butter to become a meal in its own right. I experiment with coarse salt too, and find I prefer the crunch, although the coating is not quite as even.
Oil and salt
Sometimes, it's tempting to think that everything is improved with a bit of fat. Well, I find it tempting, anyway. And, when it comes to food at least, it's usually true. So the BBC's perfect baked potato, which is massaged with oil and rubbed with salt, in the manner of a Turkish bath, seemed a sure winner.
I use British rapeseed oil, as olive seemed contrary to the whole ethos of the dish. It's more difficult to achieve an even coating with the salt than with a wet potato, but when baked, it has a better colour to it – as if it had naughtily taken advantage of the sunbeds too. The results, however, are just the same as Nigel's – satisfactorily crisp outside, and fluffy within, so the benefits of the extra fat, for once, seemed rather negligible.
Reluctant to let go of the fat idea, I also try basting a potato with melted butter before, and regularly during cooking, as suggested by posters on the cookery forum, chowhound.com, who offer duck fat or bacon grease as good alternatives. It's more time consuming, as the potato requires attention every quarter of an hour, which doesn't leave much time free for Nigel Slater's idea of sinking into a bath with a drink while dinner is cooking, but I'm impressed with the results – a skin so crisp it could fairly be described as a shell, and a perfectly cooked interior. The only problem is that most of the salt gets knocked off during the basting.
Another tip from the forums is brining – and, given what it does to bacon, it's safe to say I'm pretty interested. The American TV chef, and self-styled "kulinary gangsta", Guy Fieri, gives a recipe for "The Bomb Bakers" which calls for the potatoes to be soaked in a solution of 1 part coarse salt to 8 parts water for between 2 and 7 hours.
I do one for the minimum, and one for the maximum time, and then roll both in more salt, as directed, ignoring the number of government health warnings these potatoes are contravening. I'm expecting them to be flabby, after such a long time submersed in water, but they're both up to Nigel's standard. I can't really detect any transfer in flavour to the flesh in either, however, and it's unclear how much of the flavour is down to the brining process, and how much to the outer crust of salt, so I bake a third, brined for three hours, and then half rolled in salt. The half without the extra salt has a nicer flavour – more subtly salty – but is less crisp, which renders the whole exercise pointless.
As with sausages, the world is divided between those who prick their jacket potatoes, and those who don't. The nay-sayers claim that the departing steam prevents the skin from crisping, the yes camp sensibly point out that it stops the potato exploding, as is occasionally its wont. I've never been the victim of an angry spud, but I can well believe it's a devil to clean up after, and as, after testing I find no deficiency in texture results from piercing the skin, I shall do so in future. Some people believe that potatoes must be cooked on a wire rack, rather than a baking tray, to allow the air to circulate; I find this prevents a slightly calloused base, but has little other effect.
Finally, in terms of temperature, it's Nigel Slater versus Delia – he reckons they should be cooked between 200 and 230C, she knows better. "I used to put them in a hot oven," she confides, "but I've learnt over the years to get the crunch, they need to have slightly less heat and slightly longer cooking."
I've been cooking mine at her preferred oven temperature of 190C, but for my last spud, I crank the dial up to 220C and stick my damp, salt-crusted victim on the middle shelf. It's pretty average in size, so I set the timer for the hour suggested by Nigel, which leaves it definitely done, but lacking something in the crispness stakes, so I give it another 15 minutes. It's perfection: a crackly, crispy, salty shell, which, when I give it a good thump, splits in a cloud of steam to reveal a snowy interior of impeccable fluffiness.
The perfect jacket potato is as simple as the pleasure of eating it: a floury variety, a crust of salt, and longer than you might think in a hot oven – eat it fast though, before it goes soggy!
The perfect jacket potato
1 floury potato per person (e.g. Maris Piper, King Edward, Estima, Desiree)
About 20g coarse sea salt
1. Pre-heat your oven to 220C.
2. When the oven is up to temperature, wash the potatoes well, and prick each in a couple of places with a fork. Allow to dry slightly, while you tip your salt into a shallow bowl. Roll each potato in the salt to give an even coating, and then place on the middle shelf of the oven, preferably directly on the rack.
3. Cook for around an hour, then give them a squeeze – the potato should just give, and the skin should be distinctly crisp. If not, leave them for 10 minutes, and check again – if you overcook them, the insides will be dry, so it's important to be vigilant.
4. Take out of the oven and put whole on to plates: they shouldn't be opened until you're ready to eat, and then preferably by hitting them sharply so they burst, for maximum fluffiness. Do your thing with butter, and tuck in immediately.
Do you like your jacket potatoes tender and buttery, or so crisp you could break a tooth on them? Is there any better filling than cheese and beans? And lastly, has anyone ever managed a satisfactory spud in a bonfire?