Line a large bamboo or stainless steamer with perforated (punch a few small holes in it) round of parchment paper. Set the fish in the steamer. Cover and steam for 5 minutes, or until the fish is cooked. Transfer fish to a heated serving platter.
Place the oil in a small skillet set over high heat. Add the ginger, garlic and chilies and cook until fragrant, about 15 to 30 seconds. Remove from the heat and carefully add the soy sauce. Spoon the mixture over the salmon, sprinkle with green onion and serve. Garnish with lime slices, if desired.