no oil . the water hydrates the outer layers of the dumpling like item . longer = softer texture for some of the dumpling.
you still get crispy based on the AF time and temp
but you can get both ' steamed ' and ' crunchy ' at the same time w a soak. dont soak for very long w thin skinned items like these
thicker ' casings ' can take a longer soak . talking minutes here , not tens of minutes . directly from Fz
also tasty w no soak , directly from Fz into the AF