Mix the wet ingredients: In a large bowl, whisk together the sugar and egg until well combined. Add the yogurt, milk, and lemon zest, mixing well until smooth.

Add the dry ingredients: Gradually add the flour and baking powder to the wet mixture, stirring gently until just combined. It’s okay if there are a few lumps—do not overmix! The batter should be thick but pourable.

Heat the oil: Pour vegetable oil into a large frying pan and heat it over medium-low heat. To test the oil’s temperature, drop a small piece of dough into the oil. If it sizzles and floats to the surface, the oil is ready.

Form the donuts: There are two methods to form the donuts: Spoonful: Dip two spoons in the hot oil, then scoop up a rounded spoonful of dough. Gently slide the dough into the oil.

Piping bag: Transfer the batter to a piping bag fitted with a star tip. Pipe the batter directly into the hot oil in donut shapes.

Fry the donuts: Fry the donuts for 2-3 minutes on each side, or until they are golden brown.

Drain and coat: Transfer the fried donuts to a paper towel-lined plate to drain any excess oil. While still warm, roll the donuts in granulated sugar for a delicious coating.

Enjoy! Serve your delicious yogurt donuts warm.