Prep the mango. Peel and pit one ripe mango. Chop the flesh and add to a blender. Reserve the second mango for topping and serving.
Blend the marinade. Add olive oil, soy sauce, honey, lime zest and juice, garlic, ginger, chili flakes, cumin, paprika, salt, and pepper to the blender.
Blend until smooth and vibrant. Taste and adjust salt, heat, or sweetness as needed.
Portion the chicken. If using breasts, slice them horizontally to create even cutlets about 1/2 to 3/4 inch thick. Even thickness helps grill marks and prevents dry spots.
Marinate. Pour about two-thirds of the mango mixture into a zip-top bag or shallow dish with the chicken.
Seal and toss to coat. Marinate 30 minutes at room temperature or up to 8 hours in the fridge. Reserve the remaining marinade in a covered container in the fridge for basting and sauce.
Preheat the grill. Heat a gas or charcoal grill to medium-high (about 400–450°F). Oil the grates to prevent sticking.
For a grill pan, preheat over medium-high and lightly oil the surface.
Pat dry for better sear. Remove chicken from the marinade and lightly pat with paper towels. This helps the chicken char instead of steam. Discard used marinade.
Grill the chicken. Place chicken on the hot grates.
Grill 5–7 minutes per side, depending on thickness, until internal temperature reaches 165°F. Brush with a little of the reserved clean marinade during the last 2 minutes on each side for a glossy finish.
Make a quick sauce (optional but great). While the chicken rests, pour the rest of the clean reserved marinade into a small saucepan. Simmer 3–4 minutes until slightly thickened.
Taste and adjust with a touch more honey or lime if needed.
Slice and serve. Cube or slice the remaining fresh mango. Plate the chicken with mango pieces, a sprinkle of cilantro, and a squeeze of lime. Add your favorite sides and spoon sauce over the top.