Grill the Chicken: Season the chicken breasts with salt and pepper. Grill on medium heat for 7-8 minutes per side until cooked through (165°F internal temperature). Let it rest before slicing.
Prepare the Salad: In a large bowl, combine the mixed greens and sliced strawberries.
Make the Dressing: In a small bowl, whisk together olive oil, balsamic vinegar, salt, pepper, and honey mustard dressing (if using).
Assemble the Salad: Add the grilled chicken slices, crumbled feta, and pecans to the bowl with the greens and strawberries.
Dress and Toss: Drizzle the dressing over the salad and toss gently to combine.
Serve: Enjoy immediately or refrigerate for up to 1 hour before serving.