Ingredient

Sweetcorn

Sweetcorn starts converting its sugar to starch the moment it is picked, and it does so faster than almost any other vegetable. That single fact governs how to buy it, how quickly to cook it, and why frozen sweetcorn is often better than a fresh cob that has been in transit for four days.

The sugar clock

A cob of sweetcorn is a collection of immature seeds, and a seed's job is to store energy as starch. Sweetcorn varieties have been bred to delay that conversion, which is what makes them sweet — but they have not been bred to stop it.

Once picked, the cob is cut off from the plant and its metabolism carries on. Sugar becomes starch, and the kernels go from sweet and milky to bland and mealy over a matter of days. The old American advice about putting the water on before you go out to the field is an exaggeration of a real effect.

Two practical conclusions. Buy the freshest you can and cook it the same day. And do not dismiss frozen sweetcorn — it is picked and frozen within hours, which stops the conversion in its tracks, and it is frequently sweeter than a supermarket cob that has spent a week getting there. Modern super-sweet varieties hold their sugar longer than older ones, which has softened the problem without removing it.

How to cook it

• Boiled, briefly. A few minutes in unsalted water is enough — the kernels are already tender and you are heating them, not cooking them soft. Salt in the water is often said to toughen the kernels; the bigger risk is simply overcooking.
• Grilled or barbecued, husk off, directly over the heat until charred in patches. Char against sweetness is the whole appeal.
• Grilled in the husk, soaked in water first, which steams the kernels in their own wrapper and gives a gentler result.
• Roasted, kernels cut off and spread on a tray, until browned in spots. The best way to get corn into a salad or a salsa.
• In a hot dry pan, kernels only, tossed until they blister and pop. Fast, and excellent.
• Raw, cut off a genuinely fresh cob, in a salad. Sweet, crunchy and almost nobody tries it.
• Microwaved in the husk, which sounds unpromising and works very well — a few minutes, then the husk and silk pull off cleanly in one go.

Getting the kernels off without them going everywhere

1. Cut the cob in half across, so you have two short stable pieces rather than one long unstable one.
2. Stand a half upright on its cut end inside a large bowl, or on a board set inside a baking tray.
3. Run a knife down the cob, close to the core, turning after each cut. The bowl or tray catches what would otherwise cross the kitchen.
4. Once the kernels are off, scrape the bare cob firmly with the back of the knife. A surprising amount of sweet, starchy liquid comes out, and it thickens and enriches whatever you are making.
5. Keep the stripped cobs. Simmered in milk or water they make an intensely corn-flavoured liquid that is the base of a good chowder.

What to do with it

• Elote or esquites — grilled corn with mayonnaise, lime, chilli and crumbled cheese, on the cob or off it. The best-known treatment for good reason.
• Chowder, with the scraped cobs simmered in the milk for flavour.
• Fritters, with a light batter, spring onion and chilli.
• In a salsa with tomato, red onion, lime and coriander.
• Creamed corn, which is far better made from fresh kernels than from a tin.
• Cornbread, with whole kernels folded through the batter.
• In a stir-fry, where charred kernels work well with chilli and basil.
• With butter and salt, on the cob, which needs no improvement.

Common questions