Preheat the oven to 180°C (Fan). Line a 12-hole muffin tin with cupcake liners, or use silicone cupcake cases. For non-stick tins, you can simply grease them with butter.

In a mixing bowl, combine the vegetable oil, eggs, and caster sugar. Using an electric handheld mixer, beat until well combined and the sugar has dissolved.

In a separate bowl, mix together the sourdough starter discard and milk. Once combined, pour this mixture into the egg and oil mixture. Add the zest of a lemon and stir everything together until well combined.

In another bowl, whisk together the flour, baking powder, and salt. Gently fold the dry ingredients into the wet mixture. Be careful not to overmix; a few lumps are perfectly fine.

Divide the batter evenly between the muffin liners. If you have any batter left over, you can bake it in small greased ramekins.

Bake the muffins for about 20 minutes in the center of the oven. To check if they are done, insert a wooden skewer or a cocktail stick into the center; if it comes out clean, they are ready.

In a small bowl, combine the juice of a lemon with the additional 2 tbsp of caster sugar. Prick each muffin with a skewer, then spoon the lemon drizzle over them. Scatter some lemon zest on top as well.

Once the drizzle has soaked in and hardened, carefully remove the muffins from the tin or molds. If you've used paper liners, simply leave the muffins in them to cool on a wire rack.