Preheat the oven to 170°C/gas mark 3

Use a paring knife to cut the garlic into thick slices, then make small cuts in the lamb and push the garlic pieces into the flesh. Place the lamb shoulder into a large casserole dish or deep roasting tray

Rub the lamb shoulder all over with the base sauce from the packet. Remove the dried chilli from the spice blend in the packet and reserve for the crème fraîche. Toast the remaining spices in a dry pan over a medium heat until they become fragrant, then scatter over the top of the lamb

Mix the main sauce and the water together and pour over the lamb shoulder. Cover the tray with a layer of baking parchment, then cover with tin foil. Roast for 30 minutes, then turn down the heat to 140°C/gas mark 1, and continue to cook for 4–4 1/2 hours, until the lamb is extremely tender

To make the chilli crème fraîche, finely chop the dried chilli and combine with the crème fraîche. Season to taste and reserve in the fridge until ready to serve

To make the mint sauce, boil the vinegar, water and sugar together until they form a light syrup, then leave to cool. Finely chop the mint and add to the vinegar reduction with a pinch of salt. Taste, adjust the seasoning if necessary and reserve in the fridge until ready to serve

Next make the tacos. Mix the masa harina with the hot water and salt until a dough forms – you may need to add a little more hot water. Divide into 20 balls and press out into tortillas, either using a tortilla press lined with two sheets of parchment paper, or a rolling pin. You can use store-bought tortillas if desired

Preheat a dry frying pan over a high heat and cook the tortillas for 2 minutes on each side, the tortillas should start to brown and blister

To serve, remove the lamb from the oven and baste well with the sauce. Serve family style with the crème fraîche, mint sauce and tacos at the centre of the table