Mix sugar and milk. Stir. Sprinkle the yeast over and let stand for 5 minutes, or until foamy. Add in the flour. Stir with a wooden spoon until well combine.

Cover the dough and let it to prove for 1 hour at room temperature.

Place the starter dough into a heavy duty mixer bowl with the main dough ingredients except shortening. Knead with dough hook attachment until well combine. Add in shortening and continue knead till form smooth and elastic dough.

Place the dough in a greased bowl, cover it and let it to prove for 1 hour or until double in size.

Turn the dough out onto a floured surface, and gently roll out to 1/2 inch thickness. Cut with a floured donut cutter. Put the donuts on a floured baking sheet. Cover with a kitchen towel/cling wrap, and let rise in a warm place until they are slightly puffed up, about 30 minutes.

Heat oil in a deep-fryer or large heavy skillet to 350°F. Slide donuts into the hot oil using a wide spatula. Turn donuts over as they rise to the surface. Fry donuts on each side until golden brown. Remove from hot oil, to drain on a wire rack.