First, wash the potato under running water (no soap!). You can scrub it with a vegetable brush or just rub it with your hands. Then pat it dry with a paper towel.
Puncture about four holes in the potato, with the tip of a sharp knife or a fork. This is important, as it allows the steam to escape. Otherwise the potato may explode when you cook it. (Seriously! If you don’t puncture it, the potato will go SPLAT all over the inside of you microwave!)
If you are baking potatoes in the oven, you can rub a small amount of oil on them so that the skin gets nice and crispy. It is not necessary to rub oil on potatoes you are cooking in the microwave oven.
Place the potato on a microwave-safe dish. Check the small print on the back of the dish to be sure. Then place it in the microwave oven. (By the way, microwave ovens do not have to be preheated.)
Many microwaves have moisture sensors inside so that all you need to do is press the button that says ‘potato’ and just wait for the microwave to beep at you.
If your microwave doesn’t have a potato button, a general rule is that one 7-to-8 ounce Idaho potato takes about 7 minutes to cook. 2 will take about 11 minutes.
The microwave will often say REST. That means the potato, not you! You need to just let it sit for a couple of minutes, for it to actually finish cooking.
But remember, each microwave oven is different, so you need to stick a knife in the potato to see if it is done. The knife should slide in easily and you should be able to squeeze the potato without too much resistance.
To open a microwave ‘spud’, it needs a bit of a bash first to break the fibers apart.
First, slice the top with a knife.
Then place a folded paper towel over the microwave potato. Using the bottom part of your fist, give it a bash. Be really careful as the potato will be very hot.
Now if you give it a squeeze it should be nice and fluffy.
You can now top it with your favorite topping.
As my Irish grandfather used to say, “I’ve never met a potato I didn’t like!”
Instructions via Start Cooking
Do It And How 