In a medium bowl, combine the diced mango and avocado. Squeeze fresh lime juice over the mixture, and sprinkle with salt and pepper to taste. Gently toss the ingredients together until well combined.

Preheat your oven to broil, setting the rack about 6 inches from the heating element. In a small bowl, mix together brown sugar, chili powder, garlic powder, salt, and pepper to create a flavorful rub. Coat the salmon fillets generously with this mixture.

Place the seasoned salmon fillets skin-side down on a nonstick baking sheet. Broil the salmon for 6-8 minutes, until the flesh turns opaque and flakes easily with a fork.

While the salmon is broiling, prepare your serving bowl with a base of rice or quinoa. Once the salmon is done, place a fillet on top of the grains and pile the fresh mango avocado salsa over the salmon.