Heat the oven and prepare the tin. Set the oven to 180°C (160°C fan). Grease a 900g loaf tin and line it with parchment paper. Leaving the paper slightly overhanging on the long sides makes it easier to lift the cooled loaf out later.
Beat the wet base. Put the oil, caster sugar and eggs in a large mixing bowl. Beat them with a wooden spoon or balloon whisk until the mixture is smooth and glossy, with no separate streaks of oil.
Add the courgette and lemon. Stir in the grated courgette along with the lemon zest and juice until the green strands are evenly spread through the mixture.
Fold in the flour. Sift the self-raising flour and bicarbonate of soda over the bowl. Fold everything together gently, stopping as soon as there are no dry patches of flour. Stirring past this point toughens the crumb.
Fill the tin and bake. Scrape the batter into the prepared tin and smooth the surface level. Bake for 55 to 60 minutes, until the loaf has risen and turned golden and a skewer pushed into the centre comes out clean. Set a timer so you don’t overbake it.
Poke the hot cake. As soon as the loaf comes out of the oven, and while it’s still hot, prick holes all over the top with a skewer so the drizzle has a way in.
Mix and pour the drizzle. In a small bowl, stir together the lemon zest, lemon juice and granulated sugar. Pour it slowly over the hot cake, letting each addition soak in before adding more. It will leave a crisp, lemony layer on top as it sets.
Cool, then finish. Leave the cake in its tin until it has cooled completely. Just before serving, scatter the remaining zest over the top.
