1In large shallow glass or plastic dish or resealable food-storage plastic bag, mix garlic, rosemary, oregano, 1/2 teaspoon of the salt, 1/4 teaspoon of the pepper, 3 tablespoons of the lemon juice and 5 tablespoons of the oil. Add chicken; turn to coat. Cover or seal; refrigerate 30 minutes to marinate.
2Heat gas or charcoal grill. In small bowl, mix remaining 1/2 teaspoon salt, 1/4 teaspoon pepper, 1 tablespoon lemon juice and 1 tablespoon oil; set aside.
3Remove chicken from marinade; discard marinade. On 6 (10- to 12-inch) metal skewers, alternately thread chicken, bell pepper and onion, leaving space between pieces.
4Place skewers on grill over medium-high heat. Cover grill; cook 8 to 10 minutes, turning occasionally and basting with lemon juice mixture, until chicken is no longer pink in center and vegetables are tender. Discard any remaining lemon juice mixture.