Preheat your oven to 160°C (320°F) with the fan setting on. If your oven lacks a fan function, refer to note 1 for adjustments. Prepare an 8.5x4.5-inch loaf tin by lightly greasing it, then line it with baking parchment to ensure easy release.

In a medium-sized bowl, sift together the all-purpose flour, cornstarch, baking powder, and salt. Whisk the mixture thoroughly to combine, then set it aside.

In a separate small bowl, mix the warm milk with the lemon juice. Stir until well blended. Allow the mixture to sit for a few minutes; it will curdle slightly, which is completely normal.

Using a large mixing bowl, cream the softened butter, vegetable oil, granulated sugar, and lemon zest together for about 2 minutes until the mixture becomes light and fluffy.

Gradually add the eggs, one at a time, ensuring each is fully incorporated before adding the next.

Pour in half of the milk and lemon juice mixture. Mix gently until fully combined. Switch to a spatula or wooden spoon for the next steps to avoid overmixing.

Add half of the dry ingredient mixture to the wet batter. Fold gently until just combined. Then, incorporate the remaining milk and lemon juice mixture, followed by the rest of the dry ingredients. Fold carefully to ensure the batter is smooth but not overworked.

Transfer the batter into the prepared loaf tin, spreading it evenly. Bake for approximately 1 hour or until a skewer inserted into the center comes out clean.

Allow the loaf to rest in the tin for 15 minutes before carefully transferring it to a tray. During this time, prepare the lemon syrup.

Combine the sugar and lemon juice in a small saucepan. Heat over medium heat, stirring occasionally, until the sugar is fully dissolved. Remove from heat.

Using a pastry brush or spoon, generously coat the warm lemon loaf with the syrup, ensuring the top and sides are thoroughly soaked. Don't forget to cover the bottom as well. Handle the loaf gently, as it will still be fragile. Use all the syrup for maximum flavor. Let the loaf cool completely before proceeding.

In a small bowl, mix the icing sugar with the lemon juice until the glaze reaches a thick, pourable consistency. If necessary, adjust by adding more sugar or juice.

Once the loaf is fully cooled, drizzle the glaze over the top, spreading it evenly. For a decorative touch, sprinkle additional lemon zest over the glaze.

Let the glaze set before slicing and serving your beautifully moist and tangy lemon loaf.