Start the day before. For 2p put 125 grams of white beans in a large amount of water for at least an overnight. Boil 1 small sized frozen polpo (approximately 700 grams) for almost 1h, until tender. Drain and store in the fridge.
Drain the beans. Put them back in the pan. Add water. Heat. Once boiling, cook for almost 1h ( I prefer still still al dente).
Chop 1 onion and 1 fennel bulb. Heat a pan. Add 2 table spoons of olive oil. Bake the onion. Stir. Add the fennel and 4 chopped garlic cloves. Bake and stir. Add 1 table spoon of nduja ( specialty from Calabria; a spreadable spicy pork sausage). Stir and bake. Add 1 can of tomato sauce and 1 can of water. Add fresh thyme and the zeste of 1 lemon. Allow to simmer for 30 minutes.
Cut the polpo in parts. Add to the sauce. Drain the beans. Add to the sauce. Stir. Taste, add pepper and salt.
Allow to rest until dinner time. Reheat the sauce for 20 minutes. Finish with fresh parsley and lemon.