Flatten chicken to 1/4-in. thickness; cut lengthwise into sixteen 1-in.-wide strips. In a large resealable plastic bag, combine the lime juice, vinegar, chipotle pepper and salt; add the chicken. Seal bag and turn to coat; refrigerate for 30 minutes.
Meanwhile, for the sauce, place remaining ingredients in a food processor; cover and process until blended. Transfer to a serving bowl; cover and refrigerate until serving.
Drain and discard marinade from chicken. Thread meat onto four metal or soaked wooden skewers. Moisten a paper towel with cooking oil; using long-handled tongs, lightly coat the grill rack. Grill, covered, over medium heat or broil 4 in. from the heat for 8-12 minutes or until no longer pink, turning frequently. Serve with sauce. Yield: 16 skewers (3/4 cup sauce).