A few things about egg rolls ( I sell a lot of egg rolls):
-ALL the liquid must be removed from the filling or it will cause holes in the wrapper and you will get grease in. Chinese restaurants have centrifuges to spin out liquid. You can try a salad spinner
-Refrigerate your par-cooked egg rolls, don’t freeze.
-Obviously, they must be wrapped tightly with no leaks.
If your egg roll has no liquid and is wrapped correctly, you can even put the egg roll in the fryer at a too low oil temperature and as the temp comes up, it will not take up grease.
If you have the oil too hot (over 400*), you will burn the wrapper.