Mix the salad dressing/marinade by placing olive oil, white balsamic vinegar, sugar, tarragon, salt and black pepper in a small bowl. Stir until sugar is dissolved and ingredients are completely combined. Divide dressing in half, reserving half to dress the finished salad with. Set aside.

Place chicken breasts in a shallow container. Take remaining half of the dressing and pour it over the chicken. Turn to coat chicken with marinade. Cover, and place in refrigerator; let chicken marinate for at least 30 minutes.

Prepare a grill (inside or outside) by spraying with a non-stick spray. Cook chicken breasts on medium-high heat, turning occasionally until they reach an internal temperature of 165 degrees, and are cooked through. Grill times will vary, depending on size of the chicken breasts, but average time will be about 15-20 minutes. Once cooked, take chicken off grill, and let the meat rest for a few minutes to let internal juices redistribute. Cut chicken breasts into 1/2 inch slices.

Arrange baby spinach, strawberries, red onion slices, feta, and almond slices in individual serving dishes. Place grilled chicken slices on top of salad. Add avocado chunks, then drizzle with reserved salad dressing (do not use the dressing you marinated the chicken with). Serve, and enjoy!