Preheat oven to 350 degrees F. Coat an 9" x 4" loaf pan generously with non-stick cooking spray.
In a medium mixing bowl, combine flour, baking powder, and salt and set aside.
In a large mixing bowl use an electric mixer to combine sugar, yogurt, vegetable oil, eggs, the juice from half of the lemon (reserve remaining half for later), all of the lemon zest and the vanilla extract. Mix until well combined. Use a wooden spoon to stir in dry mixture, just until combined. Stir in poppy seeds last and mix until incorporated throughout the batter.
Transfer batter to prepared loaf pan and bake in preheated 350 degree F oven for 45 to 55 minutes, or until toothpick inserted in center of bread comes out clean. Remove from oven and allow to cool in pan for 15 minutes. Use a knife around the edges of the loaf pan to loosen the bread and then turn out the loaf onto a plate. Allow to cool completely before drizzling with lemon glaze.
To make lemon glaze, combine powdered sugar and juice from remaining half of lemon (2 to 3 tablespoons) to reach desired drizzling consistency. Drizzle over completely cooled bread.