6 lbs boneless pork shoulder (not lean), cut into 3-inch chunks
2-1/2 tsp Salt
1/2 Cup fresh Seville (bitter) orange juice
1 tsp Black Peppercorns
1 tsp Cumin Seeds
1/2 tsp Whole Allspice
3 Tbsp Annatto Seeds
6 garlic cloves
1 tsp Dried Mexican Oregano
1 large white onion, halved lengthwise, then cut crosswise into 1/2-inch slices
3 fresh or thawed frozen banana leaves
Serve with salsa, tortillas and rice
Put pork in a large bowl and rub with 1 tsp salt and 2 Tbsp juice.
Toast peppercorns, cumin, and allspice together, then cool slightly. Transfer to grinder along with annato seeds, and grind to a powder. Transfer to a small bowl.
Using the side of a large heavy chef’s knife, mince garlic and mash to a paste with remaining 1-1/2 teaspoons salt. Add to ground spices, along with oregano and remaining 6 Tbsp juice. Stir to make a paste.
Toss pork with paste to coat well. Add onion and toss to combine.
Holding both ends of a banana leaf, drag leaf over a burner on moderately high heat slowly until it changes color slightly and becomes shinier, then turn over and toast other side. Toast remaining banana leaves in same manner.
Line roasting pan with leaves, shinier sides down, by arranging 1 leaf lengthwise and 2 leaves crosswise, letting excess hang over sides. Trim overhang to about 8 inches on all sides.
Transfer pork mixture to banana leaves, then fold overhang of leaves over pork to enclose completely. Cover pan tightly with foil and chill, at least 6 hours.
Put oven rack in middle position, then put pan with pork in cold oven, then heat to 400°F (to take chill off pork gently).
Once oven is heated to 400°F, bake until pork is very tender, 2-1/4 to 2-3/4 hours.
Discard foil and open banana leaves. Serve pork with salsa and tortillas.