Mix the dough

In a stand mixer bowl. add the water, sugar, and yeast. Leave to get foamy, about 5 minutes.

Add in the flour, salt, and vegetable oil.

Knead with a dough hook until a smooth dough forms, about 5 minutes.

Leave the dough to rise

Remove the dough from the mixer bowl and form into a ball. Lightly mist the bowl with oil and replace the ball of dough into it. Cover the bowl and let rise in a warm place, 1 to 1½ hours, until doubled.

Shape and fry the doughnuts

Preheat about 5cm (2") of vegetable oil in a pot to 180℃ / 350℉ – you can use a smaller pot needing less oil to fill but cooking less doughnuts at a time, or a larger one and cook more each batch. I also like to set up a drying rack set over a paper-towel-lined sheet pan to drain the doughnuts on, so they stay crispy. You can also prep a plate with paper towels if you don't want to bother.

When the oil is at temperature, use a cookie scoop or two regular tablespoons to form a piece of dough into a rough ball shape and place in the oil. Repeat for as many doughnuts as will fit in your pot without overcrowding.

Fry each doughnut for about a minute on each side, turning halfway through. Drain on prepared rack or paper towels.

When the doughnuts have cooled slightly, sprinkle with powdered sugar.