Use a fork to poke a few holes in each of 4 medium sweet potatoes. This allows the steam to escape without exploding your potato in the microwave.
Wrap a wet paper towel around each potato. You don't want it to be dripping wet, but it should be much more saturated than damp. This helps keep them from drying out in the microwave.
Lay the wrapped potatoes on a microwave safe plate, spacing them out a little. You can skip the plate and lay them directly on the microwave turntable, but then you'll need to use tongs or potholders to remove the hot potato.
Microwave sweet potato on High power for 10 minutes for medium-sized potatoes (follow time directions noted below). Test for doneness by poking sweet potato with a knife. It should easily slide through to the middle of the softened potato. Remove the plate from the microwave and set aside until potatoes are cool enough to handle.
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Notes
If you're only cooking one sweet potato instead of four, start with about 4 minutes for a small one or 6 minutes for a medium one, then check for doneness and add more time as needed.Cook time depends on size: 8-9 minutes for small potatoes, 10-11 minutes for medium, and 13 minutes for large (all times for four potatoes cooked together).Store leftovers in an airtight container in the fridge for 3-4 days. Scoop the flesh from the skin before storing so it reheats evenly.