Preheat oven to 400°F. Spray a 6-cup donut pan with nonstick cooking spray.
In a large bowl whisk together flour, sugar, baking powder, baking soda, and salt. In a small bowl whisk together egg, yogurt, oil, and lemon juice. Make a hole in the center of the dry ingredients and pour wet ingredients into the hole. Gently fold everything together until combined. The batter will be thick; do not overmix.
Scoop batter into a piping bag or freezer bag and snip a bottom corner with scissors. Squeeze out batter evenly into prepared donut pan.
Bake for 10 minutes or until golden brown. Let cool for a few moments and then flip over onto a cooling rack to cool completely.
For Glaze:
Whisk together the glaze ingredients until smooth. Add more sugar for thickness, more lemon juice for thinness. Dip the doughnuts in glaze and place on a lined baking sheet. Let stand until glaze has set before serving.