Octopus is intimidating. And foreign to most Americans’ palate. I was weary of it, but it such a staple in Panama (where is it called pulpo), that I tried it with reservations, and loved it. I order it often at tapas restaurants, and cook it in my home kitchen more than most. Almost the entire creature is edible, so you get a good yield. It is also super-easy to prepare. After boiling, the pulpo softens enough for you to chew it easily, but retains a nice al dente texture. Pulpo has a slight seafood flavor, a bit stronger than calamari or scallops, and picks up other flavors really well. I always try to keep a whole, raw octo in my freezer, and usually have some already boiled and sliced in freezer bags, ready to be turned out into a quick dinner on short notice.
Take the whole guy (even if still frozen) and boil it until the purple outer layer begins to peel away, and a knife can pierce easily through the flesh at the point where the tentacles merge with the “body” of the octopus.
Drain, and butcher once it is cool enough to handle. You can do this by slicing off each tentacle, and cutting bite sized pieces of the remaining body, throwing the harder “mouth” piece away. You can get some meat out of the head, but you’ll have to trim away any innards. Then trim off any outer skin that is sort of hanging or clinging to the body, and slice bite-sized pieces in rings.