Preheat the oven to 350 degrees F. Line a 12-cup muffin pan with paper liners. Using a vegetable peeler, remove the zest from the lemon in wide strips, being careful not to remove the white pith. Combine the lemon zest and sugar in a food processor and process until the zest is finely chopped, scraping the bowl halfway through, about 1 minute. Stir in the poppy seeds. Scoop out 3 tablespoons of the lemon?poppy seed sugar and set aside.
Whisk the flour, baking soda, baking powder and salt in a large bowl. Whisk the remaining lemon?poppy seed sugar, the vegetable oil, buttermilk, vanilla and eggs in a medium bowl; stir into the flour mixture until just combined. Stir in the zucchini.
Divide the batter among the muffin cups, filling them three-quarters of the way. Tap the bottom of the pan lightly on the counter to smooth out the batter. Sprinkle the tops of the muffins with the reserved lemon?poppy seed sugar. Bake until the muffins are golden brown around the edges and a toothpick inserted into the center comes out clean, 23 to 25 minutes. Let the muffins cool 5 minutes in the pan, then remove to a rack to cool completely.
Photograph by Ryan Dausch