Ben Cramer’s LowCountry Exotic Mushroom Farm (see Sources) produces beautiful shiitake, portobello, and oyster mushrooms about a half hour outside Charleston on idyllic John’s Island. Encourage your grocer to carry fresh mushrooms. Most metropolitan areas now have growers such as Ben nearby to supply the growing demand for these so-called exotics. Try to find fresh oyster mushrooms with caps no bigger than 2 inches across for this dish.