In a large glass bowl, whisk together lemon juice, 4 tablespoons oil, ½ teaspoon salt,
½ teaspoon pepper, and onion powder. Add chicken, turning to coat. Cover and refrigerate for at least 2 hours or up to 6 hours.
Remove chicken from bowl, discarding marinade. Pat chicken dry. Brush with remaining 2 tablespoons oil. Sprinkle with remaining 1½ teaspoons salt and remaining 1 teaspoon pepper.
Spray grill rack with nonflammable cooking spray. Preheat grill to medium-high heat (350° to 400°).
Grill chicken until a meat thermometer inserted in thickest portion registers 165°, 4 to 5 minutes per side. Let cool for 20 minutes.
On a large platter, arrange lettuces, strawberries, tomatoes, and cucumber. Slice chicken, and place over lettuce mixture. Chicken can be served warm or chilled. Sprinkle basil and red onion over salad. Serve with Strawberry Vinaigrette.
Recipe by Southern Lady Magazine at https://southernladymagazine.com/grilled-chicken-salad-with-strawberry-vinaigrette-recipe/