Heat gas or charcoal grill. In medium bowl, mix beef, lime peel, lime juice, chili powder, tomato paste and garlic. Shape mixture into 4 sausage-shaped rolls, about 6 inches long. Thread 1 beef roll on each of 4 (11-inch) metal skewers; flatten slightly.
In another medium bowl, mix bell pepper, onion and oil; place mixture in grill basket (grill “wok”).
Place skewered beef rolls and grill basket on grill over medium heat. Cover grill; cook 7 to 8 minutes, turning beef rolls after 5 minutes and shaking basket to turn vegetables occasionally, until beef rolls are thoroughly cooked and no longer pink in center and vegetables are crisp-tender.
Remove each beef roll from skewer onto center of tortilla. Spoon vegetables over beef rolls. Top with sour cream and cilantro. Serve with guacamole.