Preheat the oven to 375 degrees.
Thoroughly grease your donut pan and set aside.
Stir flour, sugar, baking powder and salt together into a medium bowl. Or measure flour by spooning and leveling in a measuring cup, then whisk together dry ingredients.
In a separate bowl, stir buttermilk, eggs, lemon juice and lemon zest.
Add wet ingredients to dry ingredients, whisk together until well combined.
Spoon the batter into your prepared donut pan, filling each cavity ~3/4 full.
Bake for 12-14 minutes or until the edges just begin to brown and a toothpick comes out clean.
Allow the donuts to cool for 5 minutes, then turn them out on to a cooling rack. Allow them to cool completely before adding the glaze.