Note: When you are selecting your fresh portabella mushrooms for wokking up a jumbo prawn wok meal, you will want to choose the more mature mushrooms which you can identify by their more open gills and flatter cap shape. The more mature portabello mushrooms have a stronger flavor than the younger mushrooms, and this goes well in the jumbo prawn wok recipes and is a great partner to the flavors of the 'essential ingredients' of fermented black beans, fresh garlic, and fresh ginger.
An Older Portabella Mushroom with Open Gills and Flat Cap
The older portabellas may look a little beaten up, and they may be a bit dried out from having sat unwanted for a few days while other folks snap up the heavy plump portabellas, but as long as they aren't spoiled (pretty rare) they're just as good for you as the portabellas with heavy water content and will give that extra flavor and help keep your jumbo prawn wok recipes from getting too soupy as you cook them.
[Buying more mature portabella mushrooms gives you more bang for your buck as the mature mushrooms have less water weight and therefore save you money.]