Use a tall beaker which is just slightly wider than your hand blender. Add the ingredients in the order listed and pour the oil in gently so as not to disturb the other ingredients too much.
Now take your hand blender and *before you turn it on*, lower it to the bottom of the beaker. Then turn it on and let it blend for about 10 seconds. After 10 seconds, slowly raise the blender until you reach the top. Your mayonnaise should be ready.
*Important: Do not turn on the hand blender until you have reached the bottom of the beaker.