Portobello mushroom is a large brown strain of the common white
mushroom (Agaricus bisporis). Portobello mushrooms are distinguished
by their large size, thick cap and stem, and a distinctive musky smell. Because
of their size - and the thickness of their fleshy caps - these mushrooms can be
cooked in a range of different ways, including grilling and frying. They are also
known as the portobella mushroom.