Preheat the oven to 180C/350F/Gas 4. Grease a doughnut pan, and set aside.
Whisk together the flour, baking powder, baking soda, and salt. Set aside.
Whisk together the egg, sugar, vanilla, milk, yogurt, oil, lemon juice, and zest until combined.
Pour the wet ingredients into the dry ingredients, and mix until just combined. The batter will be quite thick. Gently fold in the raspberries, letting them break up as you mix. Do not overmix.
Spoon the batter into the prepared doughnut pan and smooth out the tops. Fill to the top for nice, thick doughnuts.
Bake for 7 - 10 minutes or until a toothpick inserted comes out clean. Allow to cool for 5 minutes before transferring them to a wire rack to cool completely.
For the Glaze
Whisk together the icing sugar, lemon juice, vanilla, and milk until smooth and combined. Use 1 tablespoon of milk for a thicker glaze, or 2 tablespoons for a thinner glaze.
Dip each doughnut into the glaze, and leave to set on the wire rack.
Notes
Leftover doughnuts can be stored in an airtight container at room temperature or in the fridge for up to 2 days. They also freeze well for up to 2 months. Thaw overnight in the fridge before serving.