01 - Preheat oven to 350°F (175°C). Thoroughly grease and flour a 10-cup Bundt pan.
02 - In a medium bowl, whisk together flour, poppy seeds, baking powder, baking soda, and salt. Set aside.
03 - Using an electric mixer, beat butter and sugar until light and fluffy, approximately 3 to 4 minutes.
04 - Add eggs one at a time, mixing well after each addition. Stir in lemon zest and vanilla extract.
05 - Mix in fresh lemon juice and sour cream until combined; the batter may appear slightly curdled.
06 - Gradually add dry ingredients to the wet mixture, mixing just until incorporated to avoid overmixing.
07 - Pour batter into prepared Bundt pan and smooth the surface. Bake for 45 to 50 minutes, or until a toothpick inserted into the center comes out clean.
08 - Allow cake to cool in the pan for 15 minutes, then invert onto a wire rack and cool completely.
09 - Whisk powdered sugar, lemon juice, and lemon zest together until smooth and pourable. Drizzle over cooled cake.
10 - Let glaze set for 10 minutes before slicing and serving.