Season the chicken breast with garlic powder, half of the sea salt, and half of the black pepper.
Slice the zucchini into long, thin ribbons using a mandoline or a vegetable peeler.
Heat a grill pan over medium-high heat and lightly coat with 0.5 tbsp of the olive oil.
Grill the chicken for 5-7 minutes per side until fully cooked through, then set aside to rest for 5 minutes before slicing into strips.
Quickly grill the zucchini ribbons for 1-2 minutes per side until lightly charred and tender.
In a large mixing bowl, whisk together the remaining 0.5 tbsp olive oil, lemon juice, remaining sea salt, and remaining black pepper.
Add the arugula, grilled zucchini ribbons, chopped mint, and chopped parsley to the bowl, tossing gently to coat with the dressing.
Transfer the salad to a plate and top with the sliced grilled chicken and diced avocado to serve.