How do I cook squid without it going rubbery?

The two-minutes-or-forty rule, why there is nothing usable in between, and how to prepare a squid tube.

Difficulty: intermediate
Time: 25 min
Read: 3 min

Short answer

Either cook squid for under two minutes on a fierce heat, or braise it for forty minutes or more. Anything between those two makes it rubbery, and it stays rubbery until you get to the long end.

Squid is almost entirely collagen-rich muscle. It seizes within a couple of minutes of heat and then needs a long time for that collagen to break down again. The window in the middle is genuinely unusable.

Step by step

Prepare the tube.Pull the head and innards out, remove the clear plastic-like quill from inside, peel off the purple membrane, and rinse. Keep the tentacles — cut them off just below the eyes and squeeze out the small hard beak.
Score the inside of the tube.Open it flat and cut a shallow diamond pattern into the inner surface. It curls attractively when cooked and cooks faster and more evenly.
Dry it thoroughly.Squid holds a lot of water. Wet squid steams in the pan and never browns, which is half of what makes it rubbery.
For the fast route, get the pan very hot.Smoking hot, a little oil, and cook in small batches. Ninety seconds is usually enough — it turns opaque and curls.
Take it off the moment it turns opaque.Do not wait for colour on both sides. Residual heat finishes it.
For the slow route, commit to forty minutes.Braised in tomato, wine or stock, gently, for 40 to 60 minutes. It goes tough at five minutes and then relaxes again — that is expected, not a fault.
Salt at the end for the fast route.Salt draws water to the surface, which works against browning in a quick fry. Season as it leaves the pan.
Use frozen squid without apology.Freezing breaks down some of the muscle structure, so frozen squid is often more tender than fresh. Thaw it in the fridge and dry it well.

Tips

Two minutes or forty. Nothing in between is worth doing.
Frozen squid is genuinely more tender than fresh — the freezing does some of the work for you.
Small squid are more tender than large ones; large ones are better braised.

Common mistakes

Cooking squid for five to ten minutes — That is the worst possible duration. The proteins have contracted and squeezed out water, but the collagen has had nowhere near enough time to soften, so it is at its toughest.
Crowding the pan for a quick fry — Squid releases a lot of water. A full pan drops in temperature, the squid boils in its own liquid, and it turns rubbery and pale instead of browning in ninety seconds.

If it doesn't work

Rubbery after a quick fry

Cause: Cooked too long, or pan too cool — Fix: Ninety seconds in a smoking pan, in small batches.

Rubbery in a stew

Cause: Not braised long enough — Fix: Keep going — another twenty to thirty minutes gently and it will soften.

Pale and watery

Cause: Not dried, or pan crowded — Fix: Dry it thoroughly and cook in batches.

Chewy skin

Cause: Membrane left on — Fix: Peel the purple membrane off the tube before cooking.

Questions people ask

Does soaking squid in milk tenderise it?

It is a common suggestion but the effect is modest. Time and heat are what actually decide the texture — either very short or very long.

Does the same rule apply to octopus?

The long end does. Octopus is tougher again and needs 45 to 90 minutes of gentle simmering before it is tender, after which it can be grilled briefly for colour.