In a medium-sized mixing bowl, add oil, sugar, honey, and vanilla extract. Mix until the honey is fully incorporated.
Add the eggs and sourdough starter, mixing until smooth. Then, add the milk and mix again.
Add the white flour, bran, salt, baking soda, baking powder, and any additions (such as ¼ teaspoon nutmeg). Stir until a wet batter forms.
Let the batter rest for at least 30 minutes to an hour on the counter, or overnight in the fridge for better texture and flavour.
When ready to bake, preheat the oven to 450°F. Prepare your muffin tins or silicone molds and scoop the batter into each cup, filling them completely.
Place the muffin tray in the oven, then immediately reduce the temperature to 350°F. Bake for 20–30 minutes until the edges are golden brown.
Once baked, let the muffins cool in the muffin tins or remove them from the tins if using liners.