Tinned refried beans are a vaguely guilty pleasure of mine, but these taste even better thanks to a goodly, and authentically Mexican, dollop of smoky pork fat. If you keep a pot by the stove for bacon drippings, as I do, you can use those instead, but cook some specially and you’ll be left with a few rashers of crisp streaky to top.
1. Put the drained soaked beans into a large pan with the half onion and cover with plenty of cold water. Bring to the boil, skim off the scum, then turn down the heat and stir in the oregano if using. Simmer until very tender – about 2 hours, but the time varies wildly depending on the age of your beans, so check regularly. Don’t allow the pan to boil too dry, as you’ll be needing some cooking liquid later.
2. Meanwhile, if you don’t have the benefit of a big pot of bacon drippings, put a large frying pan on a medium-low heat and line with a layer of bacon. Cook gently until golden brown on both sides, then tip into a sieve set over a bowl, making sure you get all the fat out of the pan. Repeat with the remaining bacon; you should have a generous amount of bacon fat in the bowl by the end. Don’t bother to wash up the frying pan.
3. When the beans are very tender, drain, reserving about 250ml of the cooking liquid. Mash them well along with a splash of liquid, or use a stick blender if you’d prefer a smoother texture. Finely chop the remaining onion.
4. Melt a generous few spoonfuls of bacon fat in the frying pan over a medium-high heat and add the chopped onion. Fry until soft, then add the beans. Fry for a minute or so, stirring, then stir in the reserved cooking liquid until you have a loose-ish paste – you probably won’t need it all. Season to taste.
5. Finely chop 4 of the bacon rashers and stir into the pan just before serving, along with another spoonful of bacon fat if you’re feeling authentic/reckless.