Dried Pyogo (shiitake) mushrooms are preferred over fresh ones in Korean cooking as they are more intense in flavor and taste. To top it off, dried ones are more beneficial as the sun-drying process breaks down proteins into amino acids and transforms ergosterol into vitamin D; both amino acids and vitamin D are known to exhibit antioxidant and anticancer activities, help prevent osteoporosis and promote the bone growth. The dried pyogo is very low in saturated fat, cholesterol and sodium. It is also a good source of vitamin B6, folate, magnesium, potassium, zinc and manganese, and a very good source of riboflavin (or vitamin B2), niacin, pantothenic acid, copper and selenium. (Click here for details.)
Due to the sun-drying process, this food is also loaded with (i) lecithin that is known to have significant effects on lowering cholesterol and triglycerides while increasing HDL ("good cholesterol") levels in the blood, (ii) retinol (or vitamin A) that is known to help suppress the cancer cell growth, (iii) lenthionine that is partly responsible for the flavor of pyogo and known to help lower cholesterol, inhibit blood clotting, and clear mental confusion by flushing the toxins from your system, and (iv) dietary fiber that helps prevent colon cancer.
I always have dried pyogo mushrooms handy in my freezer to make MSG-free soup anytime I want. Some are ground separately in a blender and stored separately in a jar. Some are stored in zipper bags as is, or used in cooking right way after reconstituting.
Dried pyogo is commonly used in Korean cooking: jeon, jjigae (찌개, “Korean-style stew”), gui (구이, “grill”), or jorim (조림, “braising”). You may substitute any other kinds of mushrooms for it but why don’t you give it a try for its unique flavor and taste called gamchil mat (감칠 맛, “a fifth basic taste together with sweet, sour, bitter, and salty”) and its health benefits?