Prep the chicken: Pat chicken dry with paper towels.
If using breasts, pound to even thickness for more consistent cooking. Season lightly with salt and pepper.
Make the marinade: In a blender, combine mango, chili, lime zest and juice, garlic, ginger, soy sauce, honey, olive oil, cumin, and smoked paprika. Blend until smooth.
Taste and adjust salt, lime, and heat as needed.
Marinate: Pour 1/3 cup of the marinade into a small bowl and set aside for glazing. Add the rest to a large zip-top bag or bowl with the chicken. Toss to coat.
Marinate at least 30 minutes, or up to 8 hours in the fridge.
Preheat the grill: Heat a gas or charcoal grill to medium-high (around 400–450°F). Clean and oil the grates to reduce sticking.
Grill the chicken: Shake off excess marinade and place chicken on the grill. Cook 5–7 minutes per side for thighs, 4–6 minutes per side for breasts, depending on thickness. Goal internal temp: 165°F.
Glaze and char: During the last 1–2 minutes, brush with the reserved marinade to build a glossy, caramelized finish.
Avoid flare-ups by moving pieces to a cooler zone if needed.
Rest and garnish: Transfer to a plate, tent loosely with foil, and rest 5 minutes. Sprinkle with chopped cilantro and a few red pepper flakes if you like.
Serve: Add lime wedges on the side. Pair with coconut rice, grilled corn, a simple cucumber salad, or warm tortillas for tacos.