If using raw octopus, bring a large pot of water to a boil. Dip the octopus into the water for 20 seconds and then remove. Repeat another two times until the tentacles start to curl up. Submerge the octopus in the water and cook at a steady boil until tender, 40-45 minutes; top up the water with more boiling water as needed. Remove the octopus from the water and let it drain in a large colander set in the sink.