Rinse dried scallops under running water; Soak them in water for 15 minutes; Remove them; Fill a bowl with 200ml water; Put the dried scallops in the bowl of water; Leave it for 3 hours.
Rinse and drain spring onion; Cut off any roots; Chop the remaining.
Rinse, drain, peel and slice ginger.
Rinse winter melon under running water; Scrape out the seeds; Peel it with a Y-shaped peeler; Cut it into chunks.
Rinse fish steaks; Pat-dry them with kitchen paper; Remove any bones with a pair of tweezers, and discard any skin; Put them in a mixing bowl; Marinate with seasoning (1) for 30 minutes.
Discard any shrimp with ammonia-like smell; Hold a shrimp with one hand and pull off its legs with another hand; Peel it; Discard its head; Pull off its tail; Slice its back from the top to the bottom with a paring knife, and pull its vein out; Place it a bowl with fresh water for later use (repeat this process with each shrimp)
Remove all the shrimps; Pat-dry them with kitchen paper.
Fill a stockpot with 2.3L water; Add the dried scallop soaking water; Bring to the boil over a high heat; Add the winter melon, the ginger, the shrimps and the dried scallops; Bring to the boil over a high heat again; Turn to a medium heat; Cover the pot with its lid; Cook over a medium heat for 45 minutes; Add the fish steaks and most of the spring onion; Bring to the boil over a high heat again; Stir seasoning (2) into the soup; Turn off the heat; Arrange the soup in serving bowls; Garnish with the remaining spring onion; Ready to serve.