01 - Whisk together olive oil, barbecue sauce, smoked paprika, garlic powder, onion powder, salt, and black pepper in a bowl. Add chicken cubes and toss to coat evenly. Cover and refrigerate for at least 15 minutes to absorb flavors.
02 - Combine mayonnaise, sour cream, chives, parsley, dill, garlic, lemon juice, salt, and pepper in a separate bowl. Whisk until smooth and incorporated. Gradually add milk while stirring until reaching your preferred drizzling consistency. Refrigerate until serving.
03 - Heat grill or grill pan to medium-high temperature, approximately 400°F. If using wooden skewers, soak them in water for 30 minutes prior to threading to prevent burning.
04 - Thread marinated chicken cubes onto skewers, leaving slight space between pieces for even cooking. Discard any excess marinade.
05 - Place skewers on preheated grill and cook for 8-9 minutes per side, turning once, until chicken reaches internal temperature of 165°F and develops light char marks.
06 - Spread mixed greens as a base on a large serving platter or individual plates. Arrange cherry tomatoes, cucumber, red onion, avocado, and feta cheese in sections over the greens.
07 - Place hot chicken skewers directly atop the salad arrangement. Drizzle generously with prepared herby ranch dressing. Serve immediately while chicken is warm and vegetables are crisp.