I know this is a random message, but I have noticed a trend. When I saute most Chinese greens in either non stick or stainless frying pans (i use olive oil, and add kosher salt), there is a dry white residue in the pan afterward. This happens with greens purchased at the SF Farmers Market, and several other good Asian markets. Has this happened to others? Does anyone know what this is? If you don't, any theories?