Mix together the sugar and lemon zest with your fingers until well combined and fragrant. Set aside.
Combine the flour, baking powder, soda and salt. Add in sugar and lemon zest. Set aside.
In a separate bowl or large measuring cup, combine milk and vinegar and let sit for 5 minutes. Whisk in egg, melted butter and vanilla.
Add the wet ingredients into the dry ingredients all at once and whisk until well combined and there are no lumps.
Mix in lemon juice and poppy seeds.
Heat a skillet over medium heat. Pour 1/4 or 1/2 cup measures of the batter into the hot skillet and cook until bubbles appear on the surface. Flip and cook the other side until browned.