Whisk together all the marinade / dressing ingredients in large, shallow dish. Pour out ½ cup to use as the dressing; reserve in the refrigerator for later to use as the dressing.
Add the chicken to the marinade in the shallow dish and evenly coat; cover and allow to marinade for 30 minutes.
While chicken is marinading, prepare all of the salad ingredients (except for the avocado) in a large bowl and mix.
Heat a large grill pan or cast iron skillet over medium-high heat. Remove the chicken from the marinade and add to the pan along with any marinade left over in the bowl. Grill or sear until the chicken is golden on the outside and cooked through, (about 5-6 minutes each side).
Remove chicken from the pan and allow to rest for 5 minutes. Slice thickly and arrange over salad. Slice avocados and arrange on salad. Drizzle with the reserved UNTOUCHED dressing, and serve!
Notes
For some extra creaminess, try adding a drizzle of tzatziki.