How to Make It
Toss chicken with 1 tablespoon lime juice, chipotle chiles, adobo sauce, 1/2 teaspoon salt, and 1/4 teaspoon pepper. Let stand 10 minutes. Thread chicken onto 3 (12-inch) metal skewers.
Pierce potatoes with a fork. Wrap with damp paper towels, and microwave at high until slightly tender, about 3 minutes. Cut into 1/2-inch rounds. Thread sweet potatoes and bell pepper alternately onto 2 (12-inch) metal skewers.
Whisk together 1 tablespoon lime juice, 1 tablespoon oil, 1/4 teaspoon salt, and remaining 1/4 teaspoon pepper. Brush half of dressing on vegetables.
Preheat grill to high (450°F to 550°F). Place chicken on oiled grates; grill, uncovered, until cooked through, 6 to 8 minutes. Grill vegetables, uncovered, brushing with half of remaining dressing, until tender, 4 to 6 minutes. Brush scallions with remaining dressing; grill, uncovered, until charred, 2 to 3 minutes. Chop scallions; toss with orzo, remaining 1 tablespoon oil, and remaining 1/4 teaspoon salt. Combine sour cream and remaining 1 tablespoon lime juice. Serve with skewers.