Roaster box with probe thermometer, such as La Caja China; sufficient charcoal to cook pork butt for 4 to 5 hours (about 30 pounds)
For the pork: Using a paring knife, make small slits over the entire surface of the pork. Put the pork in a large roasting pan or bowl. Combine the oil, oregano, garlic and a big pinch of salt in a blender and blend until smooth. Rub into the slashes. Cover and refrigerate at least 8 hours and up to 24 hours.
Whisk together the guava jelly, mustard, orange and lime juices in a bowl and season with salt and pepper.
Prepare the roaster box according to manufacturer's instructions.
Sprinkle the pork liberally with salt and pepper and put fat-side up on the rack over the roasting pan in the roaster box. Cook for 1 hour, flip, and cook another 2 hours. Glaze the top with the guava mixture, flip, glaze again, cover the box and cook another 30 minutes, or until the internal temperature of the pork is about 195 degrees F. You can check the meat occasionally to make sure the glaze on the top of the meat isn't burning, so you can add sufficient charcoal to keep the box hot without burning the glaze. Total cooking time will be between 4 and 5 hours. Remove the pork, tent lightly with foil and let rest 15 minutes. Pull the pork into bite-size pieces and toss with more of the guava glaze.
Lay the warm tortillas on a flat surface. Smear some Chipotle Mayonnaise on each one. Fill the center with some of the pork, some of the Sour Orange, Red Cabbage and Jicama Slaw and top each with some cilantro leaves. Fold over and eat.
Whisk the mayonnaise, pureed chipotles en adobo and lime juice together until smooth.
Sour Orange, Red Cabbage and Jicama Slaw:
Whisk together the orange juice, lime juice, honey and sugar in a large bowl. Add the jicama, onions, cabbage, carrots and cilantro and season with salt and pepper. Refrigerate for at least 1 hour before serving to allow flavors to meld.