Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan and line it with parchment paper, leaving an overhang on the sides for easy removal.

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, combine the sugar and lemon zest. Rub the zest into the sugar using your fingers until it becomes fragrant and slightly moist.

Add the eggs to the lemon-sugar mixture, one at a time, beating well after each addition until the mixture is light and fluffy.

Stir in the sour cream, lemon juice, milk, vegetable oil, and vanilla extract until well combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.

Pour the batter into the prepared loaf pan and smooth the top with a spatula.

Bake for 55-60 minutes, or until a toothpick inserted into the center of the cake comes out clean. Allow the cake to cool in the pan for 20 minutes, then use the parchment paper overhang to lift the cake out of the pan and transfer it to a wire rack. Let the cake cool completely.

While the cake cools, prepare the glaze by whisking together the powdered sugar and lemon juice in a medium bowl. Start with 4 tablespoons of lemon juice and add more if you prefer a thinner glaze.

Once the cake is completely cool, drizzle the glaze evenly over the top, allowing it to drip down the sides. Let the glaze set for about 30 minutes before slicing the cake.

Store the cake in an airtight container at room temperature for up to 2 days, or refrigerate for up to a week. You can also freeze the cake for up to 3 months.