Octopus marinated in mastiha, with Florina peppers and herbs

Clean the octopus: Cut below the eyes, remove the hood completely, and discard it. Remove and discard the mouth of the octopus.Place the octopus in a large, heavy pot over low heat, cover it, and allow it to cook. Then, reduce the heat and let the octopus simmer for about 45-50 minutes until it turns slightly pink and becomes tender. Remove from heat and let it cool. If desired, remove the purple membrane.
Cut the octopus: Slice the octopus into 8 tentacles and cut each tentacle diagonally into 1-1.5 cm round slices.
Prepare the marinade: In a medium bowl, whisk together the red wine vinegar, 2/3 cup olive oil, garlic, dried oregano, bay leaf, mastic, and peppercorns. Place the octopus slices in a large, clean jar that can hold the octopus and the marinade. Pour the marinade over the octopus. Close the jar and let the octopus marinate for at least 24 hours or up to a week in the refrigerator.
Prepare the salad: In a large bowl, combine the roasted Florina peppers and spring onions. Using a slotted spoon, remove the octopus from the marinade and add it to the bowl with the peppers and onions. Add the fresh oregano, parsley, and 3 tbsp extra virgin olive oil, and mix well to combine the ingredients.
Serve: Divide the salad among 6 individual plates. Top each plate with pieces of the marinated octopus, sprinkle with capers, and drizzle with additional olive oil if desired.