First, sprinkle some salt and pepper over the pork leg and let it rest while you prepare the sauce.

Clean and cut the pasilla chiles, then soak them in the vinegar.

Blend the chiles with the vinegar, water, half an onion, garlic cloves, cloves, the rest of the spices, dried herbs, and a little salt.

The sauce should have a marinade-like consistency. If it's too thick, add water little by little. Taste the sauce—it should be slightly under-seasoned, as it will reduce and could become too salty if fully seasoned now.

Pour the sauce over the pork leg and let it marinate for a couple of hours or overnight.

Cover with aluminum foil and bake at 400°F (200°C) for 3 to 4 hours, or until the meat is tender. Baking time may vary depending on your oven.