In a deep sauté pan or Dutch oven, heat the olive oil over medium-low heat. Add the onion, garlic and half of the parsley. Cook until the onion is translucent, about 5-7 minutes. Increase the heat to high, add the wine. Cook until the wine has evaporated. Lower the heat and add the octopus. Let the octopus simmer for 5-7 minutes.
Add the tomato passata and chili flakes, and cover the pan with a lid. Simmer over medium-low heat for 35-40 minutes or until the octopus is fork-tender. Taste and season with salt as needed. Sprinkle with the rest of the chopped parsley.
Serve with spaghetti alla chitarra. Sprinkle with toasted breadcrumbs if desired.
Notes
For the Squid Ink Spaghetti alla Chitarra: (4 servings) 400 grams 00 flour + 4 whole eggs + 1 tbsp cuttlefish inkRefer to this post for further information on spaghetti alla chitarra.