1. In a medium bowl, combine lime juice, cilantro, onion, mango, bell pepper, chili powder (if using), salt and hot sauce (if using). Toss gently and set aside.
2. Prepare enough coals for a hot charcoal fire, or preheat gas grill on high for 10 minutes with lid closed.
3. Meanwhile, generously brush both sides of salmon fillets with olive oil. Place on heated grill, skin side down; grill 5 minutes, until skin is golden brown and a crust has formed. Gently turn fillets over and grill 4 to 5 minutes more, until the center is just cooked through (longer if you prefer it well done).
4. Transfer salmon to individual plates, spoon mango salsa evenly over fillets and serve.