The day before, cut all the meat into small chunks – this will take at least 30 mins. In a spacious, heavy-based pan, fry the pancetta in the oil over a medium heat until it is crisp and the fat has melted.
Stir the onions and garlic into the crisping pancetta and cook, stirring often, for 10-15 mins until soft.
Cut the lemon into quarters lengthways, then remove the pithy core and seeds. Chop into small pieces (each with a bit of peel). Remove the pan from the heat and scoop the contents into a sieve, letting any fat drain back into the pan – and give some encouragement with a wooden spoon.
Return the pan to the heat and brown the pork in the hot fat, then stir in the beef and brown that too. Add the chilli powder and cumin, and cook over a low heat for 2 mins, stirring constantly. Add the flour and cook for a further 2 mins. Add the bay leaves, 1/2 tsp salt, the lemon, oregano, tomato purée, red wine and stock. Return the onions to the pan. Bring to a simmer, stirring often, then reduce the heat and cook, uncovered, and stirring occasionally to avoid sticking, for 2 hrs until the sauce is thick and the liquid has reduced. Add salt to taste. Cool, cover and chill overnight. Can be frozen at this stage for up to 1 month – defrost overnight in the fridge before continuing with the recipe.
Add the beans to the chilli and reheat. Serve with rice or couscous, a dollop of soured cream, slices of avocado tossed in lime juice, a splash of chilli sauce, sprinkling of coriander, and lime wedges, if you like.