Preheat your oven to 325°F.
Whisk together the flour, salt, baking powder, baking soda, and sugar in a large bowl.
In a medium bowl, whisk the eggs, buttermilk, vanilla, and oil until well combined.
Pour the wet ingredients into the dry ingredients and whisk again until smooth.
Combine the brown sugar and cinnamon in a small bowl and set aside.
Transfer half of the batter into a greased loaf pan and top with half of the cinnamon sugar.
Use a toothpick to swirl the cinnamon sugar through the batter.
Top with the other half of the batter, followed by the rest of the cinnamon sugar.
Swirl the toothpick through the batter again before topping with the turbinado sugar.
Bake for 50-60 minutes or until a toothpick inserted into the center comes out clean.
Allow to cool in the pan for 20-30 minutes before transferring to a wire rack to cool completely.