Butter a loaf pan or use cooking spray. Set aside.

In a mixing bowl, whisk the flour, salt, and baking powder.

Take 2 tablespoons of the flour mixture and add to the blueberries. Mix to coat the blueberries. Set aside.

In a large mixing bowl, add the melted butter, oil, vanilla, and lemon extract. Mix well.

Add in the sugar and sourdough discard. Mix until all ingredients are combined.

Add the eggs, one at a time, mixing well in between each addition. Set aside.

Add half of the flour mixture. Mix until almost combined.

Add the milk and mix well.

Add the remaining flour. Mix well.

Fold in the flour-covered blueberries and lemon zest.

Mix until all ingredients are combined and you don’t see anymore dry flour.

Pour into the prepared loaf pan and spread evenly.

Bake in the preheated oven for 55-60 minutes. The edges will be set, the top will be golden, and when inserting a toothpick in the middle comes out free of crumbs, the loaf is ready.

Cool in the pan for 5-7 minutes, then transfer to a cooling rack to cool completely.