Fill a pot with water and place it on the stove. Place the cleaned octopus headfirst into the boiling water, covering it with a lid. Initially, cook it at high heat, then reduce to medium heat. Cook covered for approximately 50-60 minutes. Cooking time depends on the weight and size of the octopus.
While cooking, prepare the parsley by roughly chopping it and finely chop the garlic.
Remove the cooked octopus from heat and let it cool.
Once cooled, drain and peel the octopus. Slice it thinly and transfer to a bowl. Add salt, ground pepper, garlic, and parsley to the sliced octopus.
Additionally, to step 4, add extra virgin olive oil, lemon juice, vinegar, and mix everything well. Cover the bowl with foil and refrigerate for at least 45 minutes.
The dish is ready to be served. You can also serve it with toasted bread slices.