01 - Preheat oven to 350°F. Thoroughly grease and flour a 10-cup Bundt pan, ensuring all details are coated.
02 - Whisk together flour, poppy seeds, baking powder, baking soda, and salt in a medium bowl. Set aside.
03 - Using an electric or stand mixer, cream the butter and sugar until pale and fluffy, about 3 to 4 minutes.
04 - Add eggs one at a time, beating well after each. Mix in lemon zest, lemon juice, and vanilla extract.
05 - Add the flour mixture and sour cream alternately to the wet ingredients, beginning and ending with the flour. Mix just until combined to avoid overmixing.
06 - Pour batter evenly into prepared Bundt pan and smooth the surface. Bake for 40 to 45 minutes until a toothpick inserted in the center emerges clean.
07 - Allow cake to cool in the pan for 15 minutes, then invert onto a wire rack to cool completely.
08 - Whisk powdered sugar with 2 tablespoons lemon juice, adding more juice as needed until glaze achieves a pourable consistency.
09 - Drizzle glaze over cooled cake and allow to set for 15 minutes before slicing and serving.