Preheat oven to 350 degrees F.
Grease a mini muffin pan with a non-stick baking spray or butter (I used butter). Set aside.
Prepare toppings by placing them in small bowls.
In a large mixing bowl, whisk together the dry ingredients (flour, sugar, baking powder, baking soda and salt).
In a large measuring cup, whisk together milk and lemon juice. Let stand 2 to 3 minutes until the milk sours. Add egg, vanilla and oil and whisk together.
Add the wet ingredients to the dry ingredients and stir together just until combined. Slightly lumpy batter is okay. Do not overmix!
Place one tablespoon in each muffin cup. Top with desired toppings.
Bake for 10 to 12 minutes or until the tops are puffed up and set.
Cool muffins in the pan for 10 minutes, remove from the pan.
Serve or pack into ziploc bags or containers with lids for an easy on-the-go snack.