Yes, you can substitute Shaoxing wine with another type of cooking wine, but the flavor profile might be slightly different. Dry Sherry is the closest substitute in terms of flavor profile. It offers a slightly nutty flavor that complements the dish well. Then you have Mirin, which is the Japanese sweet rice wine that will add a touch of sweetness, so you might want to adjust the amount of brown sugar in the recipe. A more neutral option would be dry white wine but it won’t add the same depth of flavor as Shaoxing wine.
There are two ways to tell if your prawns are cooked perfectly. Visually, look for the prawns to turn pink and slightly opaque throughout. The flesh should no longer be translucent. The other way would be by carefully cutting into the thickest part of a prawn. The flesh should be white, firm, and not mushy.
Chinese brown sugar and regular brown sugar are similar, but with some slight differences. Chinese brown sugar tends to be more finely ground and has a slightly coarser texture than regular brown sugar. It often has a deeper, richer molasses flavor compared to regular brown sugar. They come in blocks as well. However, in this recipe, you can use regular brown sugar as a substitute; the flavor difference might be subtle.