In a large baking dish, lay down the salmon fillets in a row. Sprinkle each fillet with a pinch of salt.
Mix Thai sweet chili sauce and chili flakes. Brush or rub the fillet with the sauce using your fingers to coat the fish evenly on top, bottom, and sides. Cover and marinate in the fridge for 2 hours. (Better if marinated overnight to soak in all the flavours). Turn the oven's broiler on High and position the top oven rack 5" to 6" below the heat source.
Line a large baking sheet with parchment paper and spray with cooking spray or brush the surface with a bit of oil. Place the salmon fillets, skin side down, on the baking sheet. Coat the fillets with the remaining marinade.
Turn on the grill function and preheat for 7 to 10 minutes. Place the tray on the top most level of the rack.
Broil the fillet for 8 minutes, rotating the baking sheet once. Remove from the oven and brush the top of each fillet with 2 tablespoons of Thai sweet chili sauce. Return to the oven and broil for another 5 minutes or until the salmon has caramelised. Serve hot garnished with chopped green onion.