1. 1. Prepare Your Baking Pan: Preheat your oven to 350 F (175 C). Grease and flour a 9×5-inch loaf pan, or line it with parchment paper, leaving an overhang on the long sides to easily lift the loaf out later. This prevents sticking and makes cleanup a breeze.

2. 2. Combine Dry Ingredients: In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, salt, and poppy seeds until they are well combined. Make sure there are no lumps in the dry mixture.

3. 3. Mix Wet Ingredients Separately: In another medium bowl, whisk together the sourdough discard, milk, melted butter, eggs, lemon zest, and lemon juice until smooth. The mixture should be uniform in color and texture.

4. 4. Combine Wet and Dry Mixtures: Pour the wet ingredients into the dry ingredients. Stir gently with a spatula or wooden spoon until just combined. Be careful not to overmix; a few small lumps are perfectly fine and will result in a more tender loaf. Overmixing can lead to a tough texture.

5. 5. Bake the Loaf: Pour the batter evenly into your prepared loaf pan. Place the pan in the preheated oven and bake for 50-60 minutes, or until a wooden skewer or toothpick inserted into the center of the loaf comes out clean. The top should be golden brown.

6. 6. Cool Before Glazing: Once baked, remove the loaf from the oven and let it cool in the pan for about 10-15 minutes. This allows the loaf to set and prevents it from breaking when you remove it. After 10-15 minutes, carefully lift the loaf out of the pan using the parchment paper overhang (if used) and transfer it to a wire rack to cool completely.

7. 7. Prepare and Apply the Glaze: While the loaf cools, whisk together the powdered sugar and 2-3 tablespoons of fresh lemon juice in a small bowl until you achieve a smooth, pourable glaze. If it’s too thick, add a tiny bit more lemon juice; if too thin, add a little more powdered sugar. Drizzle the glaze generously over the cooled loaf. Allow the glaze to set for a few minutes before slicing and serving.