When it's time to make the doughnuts, make this one. For best results, I suggest starting yesterday. Make the dough a day ahead so it has time to develop flavor. The yeast will be happier for it and then so will you for the better doughnut.
Add water, eggs, yeast and all dry ingredients to the bowl. Mix 2 minutes on low speed.
Add shortening and all old dough.* Mix 8 minutes on speed 2
Mix 3 minutes on speed 3. Finished dough will be sticky but clean the bowl.
Place finished dough in prepared bin. Refrigerate at least 4 hours, but preferably over night.
Roll to approximately 1/2 thick. Cut shapes, proof 10-20 minutes.#
Fry at 350° - 375° till done. Remove to draining rack or cinnamon sugar.
If you are making Bismarks, Allow to cool before filling.
Add the powdered sugar and corn syrup to a metal bowl.
Whisk in a teaspoon of hot water at a time. It is a small amount, but just a few drops makes the difference between a nice stiff glaze, which will run a bit on hot doughnuts, and soup which will hardly cover at all.
You can adjust the ratios as you prefer and double the recipe easily.
If you prefer lemon flavored glaze, fresh squeezed lemon juice before the water is a good way to get flavor as is fresh zest.