Note Try this recipe with smoked cumin salt and aïoli.
Take two ingredients - potatoes and oil - and you've got
yourself one knock-your-socks-off snack: the chip. Choosing the
right spud is the key. You want a floury potato, meaning it's high
in starch, as opposed to a waxy one. As a rule of thumb when you're
buying unlabelled potatoes, the floury varieties usually haven't
been brushed and are still covered in dirt. If they're labelled,
then the sebago, russet Burbank and spunta varieties are
Peeling is completely optional and you can cut your chips any way you like - we've gone for the peeled and classic fish'n'chip-shop cut here. Just remember cooking times will vary depending on the size of your chip.
If you don't have a deep-fryer at home, use a large deep-sided saucepan, with a sugar thermometer to read the temperature of the oil. Fill the saucepan two-thirds full so there's plenty of oil to fry in and enough to help regulate the temperature. This also gives the oil room to bubble up in the pan when the chips are added. (Oil that is at 190C has a tendency to spit, so be careful whenever you're deep-frying.)
Use vegetable, canola or sunflower oil - they have a high smoking point, meaning they can be taken to a very high temperature (around 230C) without burning, and the subtle flavour won't overpower the flavour of the potato like an olive or nut oil would. The oil should be clean - if it's already been used for cooking, the potato can absorb a tainted smell and taste. Drain used oil through a muslin-lined sieve to help remove the sediment. Taste the cooled oil; if the flavour is still okay it can be used again.
The secret to a great chip is to blanch it before deep-frying. Depending on your taste, there are two ways of doing this. The first, which is the favoured method among many chefs, is to blanch in preheated oil at around 130-140C for 10-15 minutes. An alternative is to blanch in boiling water briefly (as we've done here) to just cook the chip through. Blanching in oil will give your chip a crisp finish, while blanching in water creates a fluffier centre (but be careful not to overcook - floury potatoes tend to fall apart more easily when boiled).
Once your chips have been blanched, let them dry out, draining all excess oil or water. Arrange the chips in a single layer on a tea towel or absorbent paper placed on a tray, and pat dry with more paper. The refrigerator or a draughty area is a good place to leave them while they dry out.
Now you're ready to deep-fry. Make sure the oil has reached the desired temperature (about 190C) before adding the chips, and cook them in small batches so the temperature remains steady. Drain them briefly in a bowl lined with absorbent paper, season them while they're hot so the seasoning clings to the chips, and eat them straight away - before the seagulls get their chance.