Cook the octopus in a large saucepan with water, salt, 1/2 lemon and bay leaves until very soft (approx. 1 hour - 1.5 hours). The octopus really has to be very soft if the dish is to succeed.
Cut into pieces approx. 1 cm in size and wrap tightly (shaped as a loaf) in cling film, wrap very tightly with aluminum foil. Pierce holes so that any remaining liquid can drain off. Then wrap it again very, very tightly in a tea towel and tie with twine. Let rest overnight.
Then cut into very thin slices and serve on a plate with tomato tartar and avocado vinaigrette.
Tomato tartare:
Core the skinned tomatoes and cut into small cubes. Season with oil, a little vinegar, salt, pepper and rosemary. Add roasted pine nuts.
Croutons:
Warm olive oil with garlic and chilli. Fry the bread cubes in it until crispy. Mix with the tartar just before serving.
Avocado vinaigrette:
Dice the avocado very small, season with lemon, vinegar, oil, salt and pepper.