Preheat the oven to 350℉ (180℃). Grease a 12-cup bundt pan with non-stick cooking spray or brush with pan release.
Grate the zucchini (no need to peel first). If you have a very large zucchini, roughly chop the grated zucchini so that you don't have any really long strands of zucchini.
In a large bowl, whisk together the flour, baking powder, baking soda and salt. Set aside.
In a separate large bowl, pinch the lemon zest into the salt. You'll rub the lemon zest and sugar between your fingers. This process helps the zest to release it's flavor.
Whisk the sour cream and oil into the sugar mixture (you would also use an electric mixer for this). Then whisk in the lemon eggs, lemon juice and vanilla extract.
Make a well in the dry ingredients and pour the wet ingredients into the dry ingredients. Fold together until just combined. I do this with a rubber spatula. If you still have quite a few lumps - you could do a few whisks with a wire whisk or mix very briefly with an electric mixer. Do not overmix.
Fold in the shredded zucchini.
Pour/spoon the batter into the prepared pan and bake in the middle of the preheated oven for about 50-60 minutes. When finished, an inserted toothpick or cake tester should come out clean or with a few damp crumbs. If you gently nudge the top of the cake with your finger, it should feel firm to the touch.
Cool the cake in the pan for about 25 minutes, then very carefully insert to remove. You may need to tap on the pan a few times to help ease the cake out.