6cupspeanut or vegetable oil or 2 1/2 pounds shortening
For the glaze:
3 1/2cups(438 grams) powdered sugar, sifted
1 1/2teaspoonscorn syrup
Make the dough
In a large bowl, mix together all the ingredients until well combined. Let the dough rest for 5 minutes. Knead the dough with an electric mixer fitted with a dough hook or by hand until smooth and soft, about 6 to 8 minutes. Place the dough in a large oiled bowl, cover with plastic wrap and let rise in a warm place until doubled in size, about 1 1/2 to 2 hours.
Punch the dough down and turn it out onto a lightly floured work surface. Roll the dough out into 1/4-inch thickness and cut with a doughnut cutter or with a large round cutter and a small cutter for the holes. Cover the dough with a clean kitchen towel and let rise until doubled in size, about 1 hour.
At this point the just-cut doughnuts can be covered and allowed to rise in the fridge overnight. Let come to room temperature before frying.
Fry the doughnuts
Heat the oil in a large, deep, and heavy pan to 350°F. Place three doughnuts in the oil at a time and fry until golden brown, about 1 minute per side. Do not overcook the doughnuts. Drain on a paper towel-lined plate.
Make the glaze:
Mix all ingredients in a bowl with a whisk until smooth. Immerse each doughnut into the glaze. Place glazed doughnuts on a wire rack above a lined sheet pan to catch any excess glaze. Let sit for 20 minutes until glaze is set before serving.