In a large saucepan filled with 2 cups of water, cook rice according to package instructions; set aside. Stir in coconut milk; set aside.
Season chicken with salt and pepper, to taste.
Preheat grill to medium high heat. Add chicken to grill and cook, flipping once until cooked through, about 5-6 minutes on each side; set aside.
Heat olive oil in a medium skillet over medium heat. Add garlic and onion, and cook, stirring often, until onions have become translucent, about 3-4 minutes. Stir in mango, mango nectar, ginger, sambal oelek and 1/2 cup water until slightly thickened, about 3-5 minutes. Stir in lime juice.
Divide rice into bowls. Top with chicken and mango mixture.
Serve immediately, garnished with cilantro, if desired.