11. Pound chicken breasts to even 1/2-inch thickness. Season with salt and black pepper.
22. Grill chicken over medium-high heat until internal temperature reaches 165°F, about 6-7 minutes per side. Let rest 5 minutes, then slice diagonally.
33. Whisk dressing ingredients until smooth and creamy. Refrigerate 15 minutes to marry flavors.
44. Arrange spring greens on large white platter. Layer sliced chicken, strawberries, blueberries, and mandarin segments.
55. Sprinkle candied pecans and feta cheese over salad.
66. Drizzle poppyseed dressing just before serving. Serve immediately.