 Medicinal herbs, such as ginseng, lingzhi mushroom, wolfberry, "Codonopsis pilosula", and "Angelica sinensis", are often used as ingredients in cooking, as in "samgyetang".Medicinal food ("boyangshik") is a wide variety of specialty foods prepared and eaten for medicinal purposes, especially during the hottest 30-day period in the lunar calendar, called "sambok".Hot foods consumed are believed to restore "ki", as well as sexual and physical stamina lost in the summer heat.