In a medium bowl, combine diced mango, pineapple, finely chopped red bell pepper, sliced green onions, minced garlic, soy sauce, honey, fresh lime juice, grated ginger, and optional chili flakes.

Season the boneless, skinless chicken breasts with salt and pepper, and brush them lightly with olive oil. Allow the chicken to rest while you prepare the marinade.

Heat your grill to medium-high temperature, approximately 375°F to 400°F.

Place the marinated chicken breasts on the preheated grill and grill each piece for about 6 to 7 minutes per side.

In the last few minutes of grilling, spoon the reserved mango-pineapple salsa over the chicken.

Once the chicken is perfectly grilled, remove it from the grill and let it rest for about 5 minutes before serving.