Where to buy King Oyster Mushrooms?
I have seen and bought them at Dragon Star. I'm pretty sure other Asian supermarkets should have them too.
From my experiences, the king oyster mushroom (or we call it eryngii) has bigger stem with small cap, so you basically eat the stem part, while for the oyster mushroom has bigger cap and most of the time with short and small stem or no stem at all.
Eryngii has pretty meaty texture, so I really like to grill or just pan grill it (but it's good whichever way you want to cook .. stir-fried, soup, etc.). The oyster mushroom has softer texture, so I think it's pretty good to make soup. I'm Thai, so I like to use the oyster mushroom to make Tom Yum soup. It's pretty good to make stir-fried mixed veggies with the oyster mushroom too.