Place the square egg roll wrapper on a flat surface in a diamond configuration (so that a corner is facing toward you).
Squeeze the filling lightly in your palm so it’s free of air bubbles and easier to wrap. Place the filling on the lower third of the wrapper.
Roll the corner closest to you over the filling once, gently tucking it under filling. Gently press down on each side of the filling to flatten the wrapper.
Next, fold over both the left and right sides of the wrapper towards the middle. Brush the egg wash over the opposite corner of the egg roll wrapper, taking care only to brush it on the wrapper itself.
Now, with your fingers on top of the roll, continue tightly rolling the egg roll into a cigar shape until completely sealed.
Place the finished egg roll sealed side down on a wooden cutting board or a sheet pan lined with parchment paper. Repeat until you’ve assembled all the egg rolls.
