Stir egg and water together and brush each wonton wrapper with the egg wash and place a piece of mozzarella in each wonton, diagonally in one corner.
Tightly roll the stick of cheese in the wonton wrapper, tucking the sides in about halfway through the rolling, before completing and sealing.
Place wrapped mozzarella stick onto a parchment lined baking sheet, seam side down.
Repeat steps 3 and 4 until all the wontons and mozzarella sticks have been used.
Place mozzarella stick in the freezer for at least an hour.
Pour about 2 inches oil into a tall pot and preheat stovetop to 350˚F.
Remove mozzarella sticks from freezer and fry in small batches, for about 3 to 4 minutes or until the wontons turn golden brown and the cheese has melted through.
Drain onto a paper towel and lightly season with salt.
Serve immediately with warm marinara sauce.