Heat the oven to 350°F. Grease a standard 9x5 loaf pan.
Whisk together the flour, sugar, baking powder, baking soda, and salt in a medium mixing bowl. In a separate bowl whisk the egg with the buttermilk and the oil.
Pour the liquid ingredients over the dry ingredients. Gently stir and fold the ingredients until all the flour has been incorporated and a shaggy, wet batter is formed. Be careful not to over-mix.
Scrape the batter into the prepared pan and pat it into the corners. Bake for 45-50 minutes. When finished, the loaf should be domed and golden, and a toothpick inserted into the center should come out clean. Let the loaf cool in the pan for 15 minutes before removing and slicing.
Wrap baked loaves tightly in plastic wrap and store at room temperature. Baked loaves can also be wrapped in plastic and aluminum foil and frozen for up to three months.