Preheat the oven to 350F (180C). Butter and dust with flour a 9 or 10 inch (23-25cm) Bundt pan.
In a medium bowl whisk flour with salt and baking powder. Set aside.
In another bowl mix sugar and lemon zest to release the oils and create a pale yellow mixture.
Add butter and vegetable oil and mix until creamy.
Incorporate eggs one at a time. Add vanilla extract and mix to combine.
With the mixer on low, gradually incorporate flour mixture, alternating with the buttermilk.
Mix until all is well incorporated.
Pour the batter into the prepared pan.
Bake for about 45-50 minutes or until a toothpick inserted into the center comes out clean. If browns too fast, you can cover it with aluminum foil and continue baking.
Allow to cool slightly into the pan onto a rack for about 10 minutes.