01 - Preheat oven to 350°F. Grease and flour a 10-cup Bundt pan thoroughly.
02 - Whisk together flour, poppy seeds, baking powder, baking soda, and salt in a medium bowl; set aside.
03 - Beat butter and sugar in a large bowl with an electric mixer until pale and fluffy, about 3 to 4 minutes.
04 - Add eggs one at a time, mixing well after each. Stir in lemon zest, lemon juice, and vanilla extract.
05 - Alternate adding flour mixture and sour cream to the wet ingredients, beginning and ending with flour. Mix until just combined without overmixing.
06 - Pour batter evenly into prepared pan and smooth surface. Bake 40 to 45 minutes, or until a toothpick inserted comes out clean.
07 - Allow cake to cool in pan for 15 minutes, then invert onto a wire rack to cool completely.
08 - Whisk powdered sugar with 2 tablespoons lemon juice; add more juice if needed for drizzle consistency.
09 - Drizzle glaze over cooled cake and let set for 15 minutes before serving.