In a large bowl, toss pork with 2 tablespoons lime juice and seasonings; let stand 5 minutes. Meanwhile, in a small bowl, mix beans, pineapple with reserved juice, onion, cilantro and remaining lime juice., Thread pork onto four metal or soaked wooden skewers. Moisten a paper towel with cooking oil; using long-handled tongs, rub on grill rack to coat lightly. Grill kabobs, covered, over medium heat 6-8 minutes or until tender, turning occasionally., Remove pork from skewers; serve in tortillas. Top with bean mixture and, if desired, sour cream.