Octopus (polipo or polpo in Italian) is delightful when it is cooked properly -- tender and buttery soft -- and it is wonderful in summer seafood salads (such as this octopus and potato salad [Insalate di polpo e patate]) but it can be devilish to cook, going from tender to rubbery and back as it sits in the pot.
Italian kitchen wisdom says to boil the octopus with a wine cork in the simmering liquid to keep it tender, but that is apparently nothing more than an old wive's tale, unsupported by science and multiple tests. Other nations offer their own homegrown advice: Greeks apparently traditionally gave the octopus a few good whacks against some rocks, while Spaniards might insist on using a copper pot.
According to food science guru Harold McGee, the key to tender and flavorful octopus is instead blanching it for 30 seconds in boiling water and then baking it, covered, in an oven at 200 degrees Fahrenheit for a few hours. It does make sense that, undiluted by cooking water, the octopus would retain more of its flavor, but if you don't have 4-5 hours to spare for this method, then you can just either keep the cooking time minimal -- less than 5 minutes -- for a slightly chewy but still tender texture, or instead use long, slow cooking (a gentle braise over low heat) for maximum tenderness. Slow braising in a liquid will take anywhere from about 1-2 hours, depending on how many pounds of octopus you are cooking.
Another secret to tenderness is that previously frozen octopus grows tender more quickly than fresh. It might seem counterintuitive since with many types of meat and seafood freezing can have a negative effect on both texture and flavor, but with octopus (and squid), that is not the case. But you can use either fresh or frozen (which is usually much easier to find, in any case). When buying fresh octopus, it should not have any fishy smell at all -- if it does, that means it's already started to go bad.
In any case, don't be intimidated by cooking octopus at home -- it's really much simpler than you think, and doesn't require any special tricks or equipment!
- The octopus (figure 2-3 pounds for 4 servings), and your braising liquid of choice*
- *You can use other liquids besides water for braising, for example: red wine, broth or even olive oil. Broths and wine infuse the octopus with flavor and color, while olive oil helps to keep it moist and tender.
If your octopus is not pre-cleaned (all frozen octopus is pre-cleaned, and if buying fresh, you can ask the fishmonger to clean it for you): Wash and clean your octopus, removing the ink sac and internal organs by making a circular cut around the beak with a paring knife and pulling it away (the organs will come with it).
Set your octopus in a large pot with enough water to cover and bring the water to just a simmer.
Either simmer for less than 5 minutes, to 130–135 ºF/55–57 ºC (for a moist, slightly chewy texture) or simmer very gently -- at just below a slight simmer (190 to 200 degrees Fahrenheit). Timing varies depending on the weight of your octopus and how many you are cooking. For 2-3 pounds of octopus (4 servings), it will usually be between 1-2 hours, but the true test for doneness is: When a knife inserted where the head meets the legs slides in easily, it's done.
Once your octopus is tender, you can serve it in a salad (the short-cook method lends itself well to this) or mixed into a pasta or risotto. You can also grill it (my favorite method) quickly over a high flame, to crisp up the exterior.