Traditional Mexican — and Sardinian — cuisine calls for lamb to be cooked in a wood-fired or underground oven. Alternatively, you can use a conventional oven set to static mode at 200°C (392°F) for about an hour and a half to achieve a similarly tender, flavorful result. Meanwhile, in a saucepan, gently sauté the garlic in a drizzle of extra virgin olive oil. Add chili to taste and the tomato passata. Let it simmer on low heat to allow the flavors to meld, then season with salt and fresh oregano. In a bowl, mix the corn flour with salt, then add hot water and a splash of extra virgin olive oil. Knead until the dough is slightly grainy but cohesive. Let it rest for about 15 minutes. Once rested, divide the dough into eight equal portions and shape them into balls. Roll each one out gently between two sheets of parchment paper using a rolling pin, until the tortillas about 3–4 mm thick and 15–16 cm in diameter. Cook the tortillas in a hot skillet until golden on both sides. Keep them warm and stacked under a clean cloth until ready to use. When the lamb is cooked, shred the meat finely with a sharp knife until you get juicy pulled meat. Season with a pinch of salt. Assemble your Barbacoa tacos: generously spoon on the spicy sauce, add the shredded lamb, and grate plenty of Bon Sardo on top. The heat from the meat will slightly melt the cheese, intensifying the flavor in every bite.