Place chicken wings in a large bowl and season with salt and pepper. Coat with 1/2 cup of mango-chili sauce, set the rest of the sauce aside for later. Sprinkle wings with sesame seeds and cover with plastic wrap. Refrigerate for 30 minutes to 1 hour.
Grease a grill or grill pan. Grill the wings for about 5 minutes on each side, or until opaque and fully cooked through.
While wings cook, place reserved sauce in a small saucepan and bring to a boil. Reduce heat to medium-low and simmer for about 5 minutes. If the sauce is too thick, add a few teaspoons of water until the desired consistency is reached. If the sauce is too thin, continue to cook until thick.
Toss chicken wings in 1/4 cup of sauce (or brush sauce on them) and place on a serving platter.
Garnish with chopped scallions and diced mangoes, and serve with remaining mango-chili sauce on the side for dipping!
How to cut a mango: Slice off the sides of the fruit, avoiding the large seed in the center. Once you have these two sides, you can get to the flesh and slice or dice as needed. Then simply scoop it out of the skin.