Put all the ingredients for the marinade in a blender with ¾ tsp of salt and blitz until smooth. Put the ribs in a large non-reactive dish (glass or porcelain is best), cover with the marinade and chill overnight.
Remove the ribs from the fridge 1 hour before cooking. Heat the oven to 160C/fan 140C/gas 3 and line a roasting tin with a piece of foil large enough to enclose the ribs. Put a large sheet of baking paper on top of the foil, then put the ribs on top. Scrape over any left-over marinade and pour over 200ml of water. Cover with a second piece of baking paper, wrap the ribs in the paper and foil, and scrunch the edges of the foil to seal.
Bake the ribs for 2 hours, then open the foil parcel and check that the meat is cooked through and falling off the bone. Turn up the oven to 180C/fan 160C/gas 5. Lightly brush the ribs with some oil and bake for 20 minutes more with the parcel open until the top of the meat has a slight crust.
Serve the ribs straight from the oven, with black beans and salsa on the side, if you like.