Preheat oven to 350°F. Grease 9 x 5 inch loaf pan, or line with parchment paper with overhang on each side.
Whisk together flour, baking powder, and salt. Set aside.
Using a stand mixer, beat eggs, egg yolk, and sugar until light and fluffy, about 4-5 minutes. While it’s mixing slowly add olive oil with a steady stream. Mixture will become thin.
In a small bowl, whisk sour cream, lemon juice and lemon zest.
At low speed, start adding flour and sour cream mixture. Alternating by first adding flour and ending with flour. Three times with flour and twice with sour cream mixture. Mix just enough to incorporate the ingredients each time. Do not overmix.
Pour the batter into the prepared baking pan and bake for 50 minutes, until golden in colour, and when cake tester or toothpick comes out clean. Let cool on rack for about 15 minutes and slide at the ends of the pan and remove cake from pan and place on rack to cool.
Serve with fresh fruit, dust with powdered sugar or add a lemon glaze. Store in cake in an airtight container or loosely wrapped foil or plastic wrap.