I don’t doubt that the mere suggestion of microwaving fish is enough to make the hairs on the back of the internet’s collective neck stand up in culinary protest.
First and foremost: This recipe doesn’t stink up the microwave. The fish is wrapped in microwave-safe plastic wrap. (Use a high-sided plate so the wrap doesn’t directly touch the food.) Second of all, microwaves are spectacularly good at steaming. Unlike in a conventional steamer, which increases the air temperature surrounding the food, pushing the heat from outside in a microwaves generates heat inside out through vibrations of the water molecules within the ingredient. Because of this internal agitation, ingredients cooked in a microwave—including a nice fresh piece of fish—tend to cook more evenly, more quickly, and more cleanly.
Achieving a uniformly and thoroughly steamed fish is particularly important for Cantonese steamed fish, the dish I would nominate as perhaps most emblematic of Hong Kong. The dish is the epitome of the Cantonese principle of cing taam (清淡), or delicacy, which celebrates balanced, subtle flavors. Especially with fish, the goal is to coax out the natural flavors of the cut, which means greater restraint with the ingredients: Ginger is added to temper any hints of gaminess, scallions to echo the sweetness, and soy sauce to elevate its savoriness. Hot oil is splashed over the top to activate those aromatics at high heat right before the dish hits the table.
This recipe can apply to any white flaky fish, though the cooking time will vary based on the thickness of the fillet. So I advise starting at about 5 minutes and adding increments of 1 minute until the fish begins to flake. As always, the fresher the fish, the better the outcome, but the 15-minute dry cure here will help tighten the flesh of the fish, especially if the fillet had previously been frozen. If you’re unfamiliar with curing fish, this may initially seem like a lot of salt, but know that excess salt will be washed off thoroughly before cooking.