Season chicken breasts with salt and pepper on both sides.

Heat olive oil in a skillet over medium-high heat. Cook chicken for 6 to 7 minutes per side until the internal temperature reaches 165°F (74°C).

Transfer chicken to a cutting board and allow to rest for 5 minutes before slicing into 0.5-inch strips.

In a small mixing bowl, whisk together mayonnaise, honey, apple cider vinegar, and poppy seeds until smooth to create the dressing.

In a large salad bowl, combine the mixed baby greens, sliced strawberries, blueberries, and red onion.

Drizzle half of the poppy seed dressing over the greens and toss gently to coat.

Divide the salad base into four bowls. Top each with sliced chicken, toasted pecans, and crumbled feta cheese.

Serve immediately with the remaining dressing on the side.