Heat olive oil in a saucepan over low heat. Slice garlic and add to oil. Cook for 3-5 minutes until it becomes soft. Add 1 tablespoon of lime juice, pepper, and salt. Remove from heat and allow to cool.
Skewer shrimp and lay onto a foil lined baking sheet. Pour the garlic oil over the shrimp, cover, and allow to marinate in the refrigerator for at least 30 minutes but up to 6 hours.
While marinating, prepare rice as directed on package (wait longer, if you are marinating for a longer period of time).
Thinly slice onions, peel and cut mango into cubes, and chop cilantro. Mix in a bowl with remaining lime juice and refrigerate until ready to use.
Preheat oven (or grill) to 375°F. Once heated, bake shrimp for 3-5 minutes or until pink and firm; watch closely so they do not over-cook. Place onto skewers.
Serve warm rice topped with shrimp and mango salsa. Enjoy!