This makes a festive buffet dish served with "calabacitas picadas" and "ensalada rosaura". Any leftover pork is ideal as a meat filling for Mexican sandwiches.

2 cups (16 fl oz/500 ml) freshly squeezed orange juice
6 chiles anchos, seeds and membranes removed
8 chiles pasilla, seeds and membranes removed
¼ onion
1/3 cup (3 fl oz/80 ml) cider vinegar
10 cloves garlic
1 teaspoon dried thyme
3 whole clove
1 teaspoon ground cumin
1 tablespoon dried oregano
1 2-in (5-cm) stick cinnamon
3 whole allspice
2 tablespoons coarse salt
1 leg of pork, about 9 lb (4.5 kg)
2 tablespoon (1 oz/30 g) lard

- In a small saucepan, heat 1 cup (8 fl oz/250 ml) of the orange juice until warm. Toast the chiles on a comal or iron skillet, then let them soak in the orange juice for 20 minutes. Transfer the chiles and orange juice to a blender, add the onion and vinegar and purée. Set aside.
- In a mortar or a molcajete, grind the garlic, thyme, cloves, cumin, oregano, cinnamon, allspice and salt. Add the puréed chiles and stir well. Add enough orange juice to dilute the mixture until it has the consistency of yogurt.
- Use a fork to pierce the leg of pork all over. Transfer to a baking pan or dish, cover with the chile-orange sauce and refrigerate, covered, for at least 6 hours, preferably overnight. Turn occasionally.
- Two hours before roasting, remove the leg of pork from the refrigerator and smear the meat lightly with the lard. Let stand in the sauce at room temperature.
- Preheat the oven to 350°F (180°C). Cover the leg of pork with aluminum foil and roast for 2 hours, basting periodically with the pan juice. Turn the meat over, cover and roast about 1 more hour. When the meat can easily be pierced with a fork, in 2-3 hours, turn the oven temperature up to 450ºF (230ºC), uncover the meat and roast for 5-10 minutes or until browned, being careful not to let it burn. Let stand for 15 minutes before slicing.
-If you wish, you can double the quantity of the sauce and serve the extra to accompany the sliced pork.