Place octopus, vinegar and oregano in a casserole. Cover and cook for 2 hours.
Mix all dressing ingredients together and set aside.
After 2 hours remove the octopus from the oven. Strain it and let it cool.
Raise the oven temperature to broil. Place the octopus pieces on a baking sheet and grill for 4 to 5 minutes OR sear the octopus on the BBQ until slightly charred.
Place the octopus on a serving platter and pour dressing on it.