Preheat your oven to 350°. Grease and flour your bundt pan very well, or spray liberally with cooking spray.
Combine the cake mix and pudding mixes in a large mixing bowl. Whisk to combine.
Add in the sour cream, oil, eggs, water, lemon juice, and lemon zest and mix well. Using a mixer is easiest, but it's not absolutely necessary.
Pour into the prepared pan and bake for 50 to 65 minutes, until a toothpick inserted into the center comes out clean.
Allow the cake to cool completely in the pan on a cooling rack.
In a medium bowl, whisk together the powdered sugar, melted butter, lemon zest, and 2 tbsp lemon juice. The glaze should be thick enough to not run directly off the cake but thin enough to actually drizzle onto the cake. If needed, add more lemon juice or a bit of milk, 1 tbsp at a time.
Loosen the cake from the pan and turn out onto a serving plate.
Drizzle the glaze on top of the cake.