Mix 1 ½ cups traditional rolled oats with 1 cup buttermilk in a medium bowl and leave to hydrate while preparing the rest.
Turn on the oven at 350°F (180ºC). Line 12 muffin cups with paper liners. Or butter and flour them if not using paper cups. Reserve.
Sift 1 ½ cups all-purpose flour, ½ teaspoon salt, ½ teaspoon baking soda and 1 ½ teaspoons baking powder into a large bowl.
Add ½ cup white or brown sugar to the oat and buttermilk mixture and stir to combine.
Add ½ cup oil and 1 egg to the oats, or stir to mix in a medium bowl first and then add. Integrate everything well without beating. Add ½ teaspoon vanilla extract if using (I usually don't).
Add the wet ingredients to the dry ingredients and stir with a spatula or hand mixer until just combined. Don’t be tempted to beat it as it will result in tougher and less fluffy muffins.
Fill the muffin tins or paper cups no more than ¾ full, dividing the mixture as evenly as possible.
Bake for 20-25 minutes, or until a tester comes out dry.
Let cool completely on a wire rack.
Store muffins that are left in an airtight container in the refrigerator, and reheat briefly before eating. Or in the freezer for a month.
