Prep Grill: Preheat the grill to medium high heat and oil the grill grates.
Prepare Tilapia: Coat the tilapia fillets with olive oil, lemon juice, salt, and pepper on both sides.
Grill: Grill the tilapia fillets for about 4-5 minutes on each side until the meat is opaque and can be easily flaked with a fork.
Prepare Salsa: In a bowl, combine the chopped mango, red onion, cilantro, and a pinch of salt.
Serve: Serve the grilled tilapia topped with the freshly prepared mango salsa.