In a bowl mix all dry ingredients together. In a blender put all the wet ingredients but not the lemon or lime juice. Blend and transfer to the dry ingredients. Whisk well that all ingredients are well combined. Only now add the lemon juice and stir again.
Grease a cupcake tin and put two tablespoons of batter in each mold.
Bake for around 15 minutes and insert a toothpick to see if they are done. Be sure you don't 'get' a blueberry as the fruit will be juicy and doesn't give you an idea if the batter is OK.
Take the cupcakes out of the oven, let them cool a little in the tin and then transfer them onto a cooling rack.
You can prepare the cupcakes with any other fruit of course. Berries are the best choice in my opinion as they go well with the lemon.
As topping, if you like any, you can put a butter cream like I did or only icing sugar.