Preheat oven to 350 degrees Fahrenheit.
Juice the lemon into large mixing bowl. Add the other wet ingredients and whisk together.
Add the dry ingredients to a small bowl and whisk together.
Add the dry ingredients to the large mixing bowl and whisk together.
Add donut batter to donut pan and bake for 20 minutes.
While the donuts are baking, prepare the frosting by adding lemon juice to powdered sugar and whisking together in a small bowl. Add in optional food coloring.
Let donuts cool to room temperature on a drying rack. Dip donuts into frosting and enjoy!