Butterflying and marinating the pork: Lay 1 tenderloin on your cutting board and cut it in half. Now, with a sharp knife, make a horizontal cut through 1 half (you'll be cutting parallel with the board) from one long side to within 1/4- inch of the other. This will allow you to fold open the meat like a book, utilizing that 1/4-inch uncut side as a hinge. Using a meat pounder or heavy mallet, pound the pork to between 1/4 to 1/8-inch thickness.
In a food processor or blender, thoroughly puree the chipotles and all the canning sauce. With a pastry or basting brush, liberally paint the meat on both sides with the pureed chipotles. Cover and refrigerate for at least 1 hour (or up to 24 hours). Repeat with the other tenderloin pieces. (There will be considerably more chipotle puree than you need; cover and refrigerate the leftover for up to 2 weeks and use it to marinate other meat, fish, poultry or vegetables.)
Soaking the sun-dried tomatoes: In a small saucepan bring the orange juice just to a boil. Add the sun-dried tomatoes, stir well, cover and remove from the heat. Let stand, stirring once or twice, until softened, about 20 minutes.
Salsa: Scrape the soaked tomatoes and the juice into a food processor or blender, and measure in 1 tablespoon of chipotle puree. Pulse the processor until the tomatoes are rather finely chopped (not pureed). Scrape into a small serving bowl. Rinse the chopped onion under cold water, shake off the excess liquid and add it to the salsa along with the olives, cilantro and the lime juice. Stir everything together, then taste and season with salt, usually about 1/4 teaspoon. Adjust the consistency to that of an easily spoonable salsa with additional juice or water if needed. Set aside at room temperature while you cook the meat.
Searing the meat: Set a large (12-inch) heavy well-seasoned or non-stick skillet or griddle over medium-high heat. Add the lard, oil or bacon drippings, brushing or spreading it around to evenly coat the surface. (If using a non-stick surface, oil the meat instead of the pan.) When the oil is very hot (it'll just begin to smoke), lay on one of the marinated meat pieces in a single layer. Sear on one side until beginning to brown (2 to 3 minutes), flip it over, and sear the other side about 1 1/2 minutes. Transfer to a baking sheet in a single layer and keep warm in the oven. Sear the remaining meat and add to the baking sheet.
Chop or slice the meat into smallish pieces and scoop into a warm serving bowl. Set on the table along with the salsa and warm tortillas, and your meal is ready.
Recipe courtesy of Rick Bayless