Mix the lemon juice with the almond milk in a small bowl and set this aside for 10 minutes. This will form your homemade buttermilk.
Grease 2 doughnut pans with oil or butter/spread and preheat the oven to 180°C/160°C fan.
Add the flour and baking powder to a large mixing bowl. Whisk well to combine.
Add the eggs, sugar, vegetable oil, vanilla extract and almond milk/lemon juice mixture to a separate large bowl. Again, whisk to combine.
Pour the dry ingredients into the wet ingredients and whisk everything together gently until smooth. Try not to overmix.
Spoon the mixture into the prepared pans, filling each hole about 3/4 of the way.
Bake for 18-20 minutes, until risen and slightly golden around the edges.
Leave the doughnuts to cool in the pan for 5-10 minutes before transferring them to a cooling rack. They should come out of the pan easily if you flip it upside down and give it a tap.
Let the doughnuts cool for at least 20 minutes before adding the glaze.