Heat a pan large enough to hold the octopus and add 2 tablespoons of oil, then peel and chop the onion and garlic.
When the oil is hot, add the onion, garlic, bay leaves and smoked paprika and cook for 2 minutes. Add the whole octopus and some sea salt and black pepper. Put the lid on and cook for 1 hour, or until the octopus is tender. To check, insert a knife into a tentacle; it should cut through with ease. If not, continue to cook, checking every 10 minutes until it is ready.
Meanwhile, make the sauce. Preheat your grill to high. Remove the crusts from the bread, then blitz in a blender to crumbs. Cut the peppers into quarters and remove the seeds, then halve the tomatoes. Oil and season them all over, then lay skin side up on a large grill tray. Grill until the skins are blistered and blackened. Peel away the skins when cool enough to handle.
Place a frying pan over a medium heat and add 1 tablespoon of oil. When it is hot, add the nuts and fry, stirring occasionally, until golden all over. Tip out onto a plate and leave to cool.
Peel the garlic and chop. Heat another tablespoon of oil in the pan and fry the breadcrumbs and garlic until golden and crisp.
Tip the garlicky crumbs into a blender, add the tomatoes, peppers and nuts and pulse to a rough paste. Add the sherry vinegar with some salt and pepper and blend for 10 seconds. Transfer to a bowl and set aside.
When the octopus is cooked, lift it out on a tray and leave until cool enough to handle. Reserve the stock. Cut off and reserve the tentacles. Slit open the main body and remove the ink sac, stomach and eyes carefully. Chop all the main body meat up and put to one side.
When ready to serve, in a large pan, mix the cooled, chopped octopus body meat into the sauce. Trim and slice the spring onions, then add along with the beans, and 200ml of the octopus stock (or more if you prefer a ‘soupy’ dish). Heat through.
Meanwhile, place a frying pan over a high heat. Oil and season the tentacles. When the pan is hot, 1 tablespoon of oil, then the tentacles. Cook for 2 minutes on each side until nicely coloured and lightly charred.
Season the stew and share between 4 bowls. Slice the tentacles and share between the bowls. Sprinkle generously with smoked paprika and serve.