Place the celery, carrot, onion, bay leaves, peppercorns in a large pan with the water and vinegar and bring to the boil. Add the octopus and cook for 35 minutes.
Remove the octopus from the liquid and reserve the liquid to use as stock. Cut the octopus into small pieces approx 5mm long.
Heat the olive oil in a pan and sauté the garlic, chilli, and fennel for 3 - 4 minutes. Add the tomatoes, octopus, 1 ½ cup of the octopus stock, the herbs and olives. Simmer for 40 minutes.
Serve with wholemeal pasta and steamed green veggies or salad.