Preheat oven to 350°F (175°C) and prepare a loaf pan or 9×9 pan with nonstick spray.
In a large mixing bowl, beat oil, sugar, and eggs until smooth and well combined.
In a separate bowl, mix flour, baking powder, and salt.
Add dry ingredients to the wet mixture gradually, alternating with milk and sourdough starter. Mix on low until just combined.
Stir in lemon zest and lemon juice by hand.
Pour batter into the prepared pan and smooth the top.
Bake for 40–60 minutes depending on pan size, until golden and a toothpick inserted comes out clean.
Let the cake cool in the pan for 15 minutes.
Mix powdered sugar, lemon zest, and lemon juice to make the glaze.
Pour glaze over the warm cake and allow it to set.
Remove from pan, cool completely, slice, and serve your Glazed Sourdough Lemon Cake Recipe.