Preheat oven to 265°F/130°C combi steam. If your oven has variable steam settings, select 30%. If not, don’t worry! Just set to combi steam at the correct temperature, and the oven will figure out the humidity.
Clean and trim the cheeks, and cut each one in half (if you buy yours from the butcher, you can ask them to do this for you).
Remove the stem from the ancho chili, roughly chop and put in a small dish covered with boiling water to rehydrate. Set aside for 5 minutes.
Put everything from the garlic to the salt into a food processor or blender (including the water from the chili) and blend into a paste. Add the beef stock and the juice of the limes and blend again to combine.
Put the beef into a baking dish or pot where it fits fairly snugly, pour over the sauce and give it a mix. Place in the preheated oven (no lid necessary) and cook until the meat is falling apart and tender, anywhere from around 3 hours and up to 5. Turn the cheeks over in the sauce a few times while they cook and if the liquid dries up, add a little water.
When the cheeks are cooked and you have a thick, dark sauce, take the dish out of the oven and use two forks to pull the meat apart. Return it back to the sauce as you shred to mix in with all of that rich, juicy goodness.
Serve meat piled into soft tortillas or crispy taco shells with sliced avocado, extra lime and coriander/cilantro, crunchy salad vegetables and your favourite spicy chili sauce.