Start by thoroughly rinsing and scrubbing the sweet potato to remove any dirt or debris. Pat it completely dry using a paper towel. Use a fork to pierce the sweet potato evenly all around, making 5 to 8 small punctures.
Wrap the sweet potato in a paper towel and place it on a microwave-safe plate. Set the microwave to 5 minutes on high. After about 2 ½ to 3 minutes, carefully open the microwave and turn the potato over with an oven mitt or a doubled-up towel to ensure even cooking.
At the end of the 5-minute cycle, carefully remove the potato. The skin should appear slightly loose. Test for doneness by inserting a knife into the skin—if it pierces through smoothly to the center, the potato is ready. If it’s still firm, continue cooking in 30-second intervals, checking each time until it reaches the desired softness.
Let the potato rest for a minute or two. Slice it down the middle and gently press to open. Add a pat of unsalted butter on top, letting it melt into the warm flesh. Sprinkle with flaky sea salt and a dash of coarse black pepper for a hint of spice, if desired.