Turn your grill (or grill pan) on to medium-high heat.
Pat the chicken breasts dry with paper towels.
In a small bowl, mix olive oil, salt, pepper, and garlic powder.
Rub the oil mixture all over the chicken breasts.
Grill chicken for 6-8 minutes per side until internal temperature reaches 165°F.
Let the chicken rest for 5 minutes, then slice or chop.
Whisk together balsamic vinegar, olive oil, Dijon mustard, honey, salt, and pepper for the dressing.
In a large bowl, combine mixed greens, strawberries, goat cheese, pecans, and red onion (if using).
Add grilled chicken to the salad.
Pour balsamic dressing over the salad, toss gently, and season to taste.