Clean and wash the fish, pat dry with paper towels.
Slash crosswise on both sides of the fish at 1 1/2 inch (4 cm) intervals.
Rub salt on both the inside and the outside of the fish and place it in a shallow bowl. (If the fish is too long for the bowl, cut it in half vertically to steam. Restore it to its original length after steaming.)
Mix the sauce ingredients in a bowl.
Pour this mixture all over the fish.
First boil the water.
Then place the fish and the bowl on the steaming rack.
Cover tightly and steam over high heat fop about 20 minutes.
Remove the bowl and transfer the fish and sauce to a larger platter.