Whisk together all of the dressing/marinade ingredients until well combined.
Slice chicken in half lengthwise to make two thinner pieces. Place the chicken in a shallow baking dish or bowl and pour half of the marinade over, turning to coat.
Let the chicken marinate for 20 minutes, then either grill it or cook it up in a cast iron skillet over medium-high heat on your stove top until cooked through (about 4-5 minutes a side, depending on thickness).
While the chicken is marinating, cut up the avocado and green onions.
Let the chicken cool, then slice it into strips.
Assemble four individual dinner salads, topping the spring mix with chicken strips, blueberries, pepitas, avocado, feta, & green onion.
Drizzle with reserved dressing and serve.
Notes
If you can't find pepitas, just substitute something else small and crunchy -- sunflower seeds would work well.