In a small bowl, whisk all marinade ingredients together to combine.
Pour a third of the marinade into a shallow dish to marinade the chicken filets for one to two hours in the refrigerator.
Refrigerate the reserved UNTOUCHED marinade to use as a dressing.
Heat about a teaspoon of oil in a grill pan or skillet over medium-high heat and grill chicken fillets on each side until golden, crispy and cooked through...just a few minutes per side. Once chicken is cooked, set aside and allow to rest.
Wipe pan over with paper towel; drizzle with another teaspoon of oil and grill or fry peppers until soft.
In a large bowl or platter, Place the mixed salad leaves, mango, avocado and green onion.
Slice chicken into strips and add it to the salad together with the peppers.
Drizzle with remaining, unused dressing, toss and serve.