First, scrub the potato until it is definitely clean. Root vegetables need extra cleaning, having come from the earth.
Next, pierce the sweet potato all over with a fork. This is really important. When you microwave a sweet potato, steam gathers between the flesh and the skin. If you don’t pierce it 8 or 10 times, your potato is going to explode in the microwave! You only need to break the skin, so don’t force your fork too deep inside the potato. You can get the same results by cutting a large X shape on the top.
Take a damp paper towel and loosely wrap your sweet potato in it. Make sure you don’t rip the paper towel. The paper towel will create a steaming effect on the baked sweet potato, making for a soft and fluffy inside and preventing it from shrinking.
Cook your sweet potato in the microwave for 4 minutes on full power. After 4 minutes, turn it over and cook for a further 4 minutes. Afterwards, poke it with a fork to test its softness. Depending on the size of the potato and how many you’re making, it should be ready about now. If not, put it back in for 2 or 3 minutes.