|1 large white onion (halved)|
|1 whole pineapple (peeled, cut crosswise into 1/2-inch-thick rounds)|
|1/2 cup fresh orange juice|
|1/4 cup distilled white vinegar|
|1/4 cup guajillo chile powder|
|3 cloves garlic (halved)|
|2 tsp coarse kosher salt|
|1 tsp dried oregano (preferably Mexican)|
|1 tsp ground cumin|
|1 1/2 tsp adobo (canned chipotle chiles in adobo)|
|3 lbs boneless pork loin (cut into 1/2-inch slices)|
|1/4 cup chopped fresh cilantro|
|10 corn tortillas|
|12 oz Smoky Two-Chile Salsa (one jar)|
|2 medium limes (wedged)|
|1 large chipotle chiles (or 2 small)|
Coarsely chop 1 onion half. Coarsely chop 2 pineapple rounds, discarding core; cover and chill remaining pineapple. Place chopped onion and chopped pineapple in blender. Add orange juice and next 7 ingredients; puree marinade until smooth. Place pork in large resealable plastic bag. Add marinade and seal bag, releasing excess air. Turn to coat. Chill at least 4 hours and up to 1 day.
Prepare barbecue (medium-high heat). Grill remaining pineapple until warm and slightly charred, 4 to 6 minutes per side. Grill pork with some marinade still clinging until slightly charred and cooked through, 2 to 4 minutes per side. Transfer pineapple and pork to work surface; chop pineapple into 1/2-inch cubes, discarding cores. Chop pork. Transfer to platter; toss to combine.
Meanwhile, finely chop remaining onion half and place in medium bowl. Add cilantro; toss to combine. Grill tortillas until warm and slightly charred, about 10 seconds per side.
Serve pork-pineapple mixture with onion-cilantro relish, Smoky Two-Chile Salsa, and lime wedges.