Finely chop the rosemary. Half will be used to make the vinaigrette while the other will season the chicken.
Make the vinaigrette by combining oil, vinegar, garlic paste, mayonnaise and rosemary in a jar with a lid.
Seal the jar and shake vigorously to combine. Set aside while you prepare the chicken.
Sprinkle the chicken with the rest of the rosemary and a pinch of salt and pepper.
Heat a skillet to medium and cook the chicken for about 20 minutes, turning half way through. Make sure the chicken is cooked to an internal temperature of 165°F.
Set the chicken aside to rest.
Assemble the salad on a large platter or in individual bowls with a base of spring greens followed by the cherry tomatoes, sliced onion, and avocado.
Slice the chicken and place on top of your salad. Sprinkle with Parmesan and drizzle with dressing.