1. Whisk mayonnaise, pineapple juice, cilantro, garlic, and chipotle in large bowl: reserve ¼ cup mayonnaise mixture. Add pineapple chunks, coleslaw mix, scallions, and ½ teaspoon salt to bowl with remaining mayonnaise mixture and toss to combine.
2. Pat pork dry with paper towels and season with salt. Rub with reserved mayonnaise mixture and grill over hot fire until browned all over and meat registers 145 degrees, about 6 minutes. Transfer to cutting board, tent with foil, and let rest 5 minutes.
3. Grill tortillas over hot fire until lightly charred, about 15 seconds per side. Slice pork thin, arrange on tortillas, and top with coleslaw. Serve.
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