Whisk the wet ingredients (oil to vanilla) in a mug.
Add in the dry ingredients and fold till all moist. Fold in the blueberries.
Microwave for 1 minute and 45 seconds. (Mine is a 1000 W oven)
Allow to cool slightly. Dig in.
Notes
Microwave time depends upon the powder of your oven. Cook a little more if you feel it is raw, but not so much that the mug cake may burn. They continue to cook even after when out of the oven.