Activate the Starter: Make sure your sourdough starter is fed and bubbly. You’ll need it to be active, so it can help the donuts rise. If your starter isn’t quite ready, feed it the night before and let it sit at room temperature overnight.
Mix the Dough: In a large bowl, combine your sourdough starter, flour, sugar, and salt. In a separate bowl, whisk the eggs, milk, melted butter, and vanilla extract. Gradually add the wet ingredients to the dry ingredients, mixing until a dough forms.
Knead the Dough: Once your dough has come together, knead it on a floured surface for about 5-10 minutes until it becomes smooth and elastic. You can also use a stand mixer with a dough hook for this step.
Let it Rise: Place your dough in a lightly oiled bowl, cover with a damp towel, and let it rise in a warm spot for about 2-4 hours, or until it has doubled in size.
Shape the Donuts: After the dough has risen, punch it down and roll it out to about 1/2 inch thickness. Using a donut cutter or two round cookie cutters (one large and one small), cut out the donut shapes. Place the donuts and holes on a parchment-lined tray.
Air Fry the Donuts: Spray or grease the air fryer tray. Place the doughnuts on the tray and spray with extra oil. Close the air fryer. Turn on the air fryer to 350°F (175°C). Fry the donuts in batches, being careful not to overcrowd the pot. Fry for about 2-4 minutes per side, until golden brown and crispy. Use a fork or tongs to remove them from the hot tray and place them on cookie sheet or baking rack.
(If you don't have an air fryer) Oil Fry the Donuts: Heat vegetable oil in a deep fryer or large pot to about 350°F (175°C). Fry the donuts in batches, being careful not to overcrowd the pot. Fry for about 1-2 minutes per side, until golden brown and crispy. Use a slotted spoon to remove them from the oil and place them on paper towels to drain excess oil. Glaze or Dust with Sugar: You can coat your fresh sourdough donuts in a simple glaze (made from powdered sugar, milk, and vanilla) or roll them in cinnamon sugar for an extra flavor boost. You can also dip them in chocolate glaze or enjoy them plain to really savor the sourdough flavor.
