Preheat oven 375 degrees F.
Prepare a loaf pan by cutting parchment paper to fit bottom of pan. Spread butter on bottom of pan and place parchment on top so paper will stick. Butter and flour top of parchment paper and sides of pan. Tap excess flour into sink.
In medium bowl sift flour and baking powder together and stir in salt, and set aside. In large bowl mix sugar and lemon zest together. Add yogurt, vanilla and eggs. Whisk until well blended.
Gradually add dry ingredients until blended, do not over mix. Fold in vegetable oil and pour batter into prepared pan; smooth top, tap pan on counter to remove any air bubbles in cake batter.
Turn oven down to 350 degrees and bake for 50-55 minutes, or until cake is golden brown and a cake tester or toothpick inserted into the center of cake comes out clean. If cake surface is becoming too brown before finished baking, cover the pan with tin foil and cook until done as specified above.
When cake is removed from oven, insert a toothpick ¾” deep into the cake, making holes all over the cake surface. Spoon lemon syrup (below) all over the top of the cake.
Let cake cool on a wire rack for 20 minutes, then run knife around the inside edge of the cake pan and invert cake onto a baking rack. Turn cake right side up and leave cake on rack until completely cool. If not serving cake right away, place cake in sealable plastic bag and refrigerate. This can be made a day ahead.