1 medium red onion, cut into 1/2-inch thick slices
8 cups baby spinach leaves
1 lime, cut into wedges
Combine 3 tablespoons Wish-Bone® Guacamole Ranch Dressing with chili powder and ground chipotle chile pepper in small bowl. Pour 1/2 of the dressing mixture over chicken in large, shallow nonaluminum baking dish or resealable plastic bag; turn to coat. Pour remaining dressing mixture over red peppers and onion in another baking dish or resealable plastic bag. Cover, or close bags, and marinate in refrigerator at least 30 minutes, turning once.
Remove chicken and vegetables from marinades, reserving vegetable marinade. Grill or broil chicken and vegetables, turning and brushing with reserved vegetable marinade, chicken is thoroughly cooked and vegetables are tender, about 15 minutes. Thinly slice chicken and peppers and chop onion.
Toss hot chicken and vegetables with spinach to wilt slightly. Serve drizzled with remaining Dressing and lime wedges.