
If you're using wooden/bamboo skewers, make sure to soak them in water for 20-30 minutes before you use them.
In a large bowl, whisk together the olive oil, lime juice, lime zest, chili powder, cayenne, salt, and sugar. Place in a bowl, or zip-top bag and add the chicken and mangoes, stirring gently to coat with marinade. Cover and refrigerate for 2-4 hours. Prepare grill (or indoor grill pan) to medium heat.
Remove the chicken and mangoes from the marinade and thread onto skewers, alternating the pieces and dividing them evenly.
Arrange the skewers on the grill and cook, turning until the chicken is nicely charred and cooked through to an internal temperature of 165°F, 6-10 minutes. Serve immediately.