Prepare dressing by combining all dressing ingredients in a bowl and whisking to combine.
Heat a large skillet over medium heat and add avocado oil. Season chicken with salt and pepper on both sides. Once the pan is hot, add chicken and cook on each side for about 4-5 minutes, until golden brown and cooked through. Turn off heat and pour about 1/4 of the dressing in the pan. Turn the chicken over a couple of times to coat with the dressing. Set chicken aside to rest while you prepare the salad.
Cut up lettuce, mango, avocados and green onion as noted. Place everything except avocados in a large bowl. Toss salad to mix ingredients. Pour in remaining dressing and toss again.
Cut chicken into small strips. Serve salad topped with chicken, avocados and roasted peppers.