Submerge the ancho chillies in just-boiled water for 20 minutes to rehydrate. Drain, pat dry then discard the stalk and roughly chop the chillies. Put in a bowl and add the coffee, Madhūka Powder, paprika, cinnamon, cumin, garlic salt, pepper and balsamic vinegar. Mix to create a paste then rub this all over the lamb. Cover and chill for a minimum of 4 hours, ideally overnight.

Remove the lamb from the fridge 1 hour before you are ready to cook it, to come to room temperature. Preheat the oven to 140°C, fan 120°C, gas 1. Put the onion wedges in the bottom of a roasting tin that’s just large enough to hold the beef. Sit the joint on top, then pour the stock around it. Cover with a few sheets of foil, tucking them tightly around the edges of the tin to create a mini-oven effect, and roast for 4 hours, turning the joint halfway through the cooking time and re-covering.

Remove from the oven and increase the temperature to 200°C, fan 180°C, gas 6. Turn the lamb and return to the oven for 20 minutes, uncovered. Remove the meat and leave to rest, covered, on a board. Tip the onions and cooking liquid into a wide pan and bubble on the hob for 15 minutes, or until the liquid has reduced to a glossy sauce-like consistency.

To serve, slice the lamb and spoon the onion sauce over. We recommend serving with our Madhūka Mole sauce in a corn tortilla wrap!