This is one of the easiest and best ways of cooking fresh fish. My mother taught me that the rule-of-thumb is that fish should be cooked for 10 minutes for each 2.5cm of thickness. This works for all cooking methods.
Steamed fish, Cantonese-style
1 whole fresh fish (get the fishmonger to kill, scale and clean it)
Fine sea salt
1-2 tbsp brandy or cognac or rice wine
Lots of finely julienned, peeled ginger
About 1/4 cup of soy sauce
About 3 tbsp oil
Lots of finely julienned spring onions
A handful of fresh coriander, roughly chopped
Step 1: Rinse the fish thoroughly under cold running water, making sure it's been well cleaned and that no scales remain. Pat dry inside and out with paper towels. Take a sharp knife and in the thickest part of the fish, make two or three deep cuts all the way to the bone.
Step 2: Sprinkle the fish very lightly inside and out with salt. Rub brandy, cognac or rice wine into the flesh. Place the fish in a heat-proof dish. Sprinkle with the julienned ginger and drizzle with the soy sauce.
Step 3: Heat water in the bottom of a two-tiered Chinese steamer. When the water boils, put the fish in the top part of the steamer. Cover and steam for 10 minutes for every 2.5cm thickness of fish.
Step 4: Just before the fish is ready, heat the oil until very hot but not smoking. As soon as the fish is cooked, remove from steamer, sprinkle with the spring onions and coriander and drizzle with the oil. It will sizzle and wilt the vegetables. Serve immediately.