Preheat the oven to 350 degrees with the rack set in the center. Spray a 9×5-inch loaf pan with nonstick cooking spray and line with parchment, leaving a two inch overhang on both sides. Spray parchment.
In a large bowl, whisk together the yogurt, sugar, eggs, lemon juice, zest, vanilla and vegetable oil until smooth. Sift in the flour, baking powder and salt, then whisk to combine. Stir in poppy seeds.
Transfer batter to the prepared loaf pan and bake until a toothpick inserted into the center of the cake comes out clean, and the loaf is a deep golden brown, 55-60 minutes. If edges begin to brown too much, cover pan with foil.
Remove from the oven and allow to cool in the pan on a cooling rack for 15 minutes.
Use parchment sling to remove loaf from pan and place on a cooling rack until completely cooled.