2) Heat 240ml oil in a frying pan, add onions, garlic and green peppers. Add 175g of the cooked beans to the pan and mash.
3) Add this to the beans together with the salt, pepper, if using, oregano, bay leaves and sugar. Allow to boil for a 1 hr then add the wine and vinegar allowing to cook uncovered for a while. Add the remaining 4 tbsp olive oil just before serving.