In a large pot, melt the butter in the vegetable oil. Add the shallots, season with salt, cover and cook over moderate heat, stirring a few times, until the shallots are softened, 5 minutes. Add the corn kernels and cook for 4 minutes, stirring. Add the ginger and wine and cook over moderately high heat until the wine is almost evaporated, 2 minutes. Add 3 cups of the stock and bring to a boil. Cover and simmer over moderate heat until the corn is tender, about 5 minutes longer.