Octopus has a bad reputation for being tough and rubbery when cooked at home. However, if you know the secrets to tenderizing it you will be able to make this exotic (outside of Italy, anyway) salad with just the right bite!
When you buy fresh octopus, you need to either freeze and thaw it or beat it vigorously to tenderize it before cooking. If your fish-monger has fresh octopus ask him if he will tenderize the octopus for you. Otherwise, when you get home spend about half an hour banging on the stiff invertebrate or flinging it against your neighborhood's rocky landscaping to counteract the rigor mortis or... you can just put it in the freezer.
I let the octopus defrost for a day in the refrigerator before using it for this recipe. from the Hip Pressure Cooking website