Lebkuchen are a kind of soft German gingerbread cookie. My mom has been making this recipe every Christmas for as long as I can remember.
Take off heat and add flour, gingerbread spice mix and salt and stir with a wooden spoon or spatula until combined. Return saucepan to the stove. Continue heating the dough while stirring until it thickens and starts to pull away from the sides.
In the meantime, beat the egg white until stiff. When the dough as cooled, stir/knead in the stiff egg white, baking soda and liquor.
Prepare several sheets of parchment paper. Divide the dough into 3-4 portions. Place each on a piece of parchment and shape into a log. Place another parchment paper sheet on top and roll the dough out with a rolling pin (thickness doesn't matter too much at this point, but about 1/4 inch works well).
Place the rolled out Lebkuchen dough in the freezer or fridge until thoroughly chilled through.
Flour your work surface. Then take one chilled dough sheet at a time and, adding only as much flour as needed to keep it from sticking to the work surface and rolling pin, roll to about 1/8-inch thickness.