Cooking Cantonese Steamed Fish with Ginger and Spring Onion is straightforward if you follow these simple steps:

1. Prepare the Fish: Clean and scale the fish thoroughly, then pat it dry with paper towels. Place it on a steaming plate or large heatproof dish.
2. Season: Sprinkle a pinch of salt and pepper inside the cavity of the fish. Add a couple of slices of ginger inside the fish for added flavor.
3. Ginger and Spring Onion Topping: Place the remaining ginger slices and half of the spring onion on top of the fish.
4. Steam the Fish: Fill a pot with water and bring it to a gentle boil. Place the steaming rack over the pot and position the dish with the fish on the rack. Cover and steam for 15-20 minutes, or until the fish is cooked through and flakes easily with a fork.
5. Prepare the Sauce: In a small bowl, combine soy sauce and sesame oil. Adjust the taste according to your preference.
6. Finish Off: Once the fish is cooked, carefully remove it from the steamer. Drizzle the sauce over the fish, then top with the remaining sliced spring onions.
7. Garnish: Add fresh cilantro leaves for garnish. Serve with lemon or lime wedges on the side, if desired.

These straightforward steps allow you to create a wonderful Cantonese dish that will impress everyone at your dining table.