Once upon a time Cantonese cuisine was the shiny new thing. Then again, there was a Gold Rush going on back then. Now “regional Chinese” is all the rage (as if Guangdong Province’s Cantonese were not one of China’s eight great regional cuisines). Sichuan was flavor-of-the-month last decade, now it’s Hunan’s turn and Shaanxi’s. Cantonese, meanwhile, is yesterday’s news. Fuan Garden Seafood Restaurant (4768 Convoy St.) aims to change that.