Preheat oven to 400 degrees F. Line a baking pan with parchment paper.
Heat the oil in a small saucepan over medium heat. Add the garlic, onion, and pepper and cook until softened. Add the mango and stir in the quinoa. Stir and cook for a minute. Season with salt and pepper.
Add water or broth and bring to a boil. Reduce to a simmer, and cover. Cook for 15 minutes, and turn off heat. Let sit, covered, for 5 minutes. Uncover and stir in the parsley.
Lay the salmon filets, skin side down, on your baking sheet. Season with salt and pepper. Spoon the quinoa mixture over the salmon and spread it evenly overtop, pressing down lightly.
Drizzle with a bit of olive oil and bake for 10-12 minutes, until salmon is cooked to your liking. Serve immediately.