Stove top pressure cooker – depending on the six of your pressure cooker, add whole potato or cut into 2 pieces. Add enough eater to cover it properly but do not overflow the water. Close the lid and let it cook until 4-5 whistles. Turn it off and let it release pressure on its own. This will take bout 10 minutes. Once done open the lid and drain the water. Let it cool down. Instant pot – add water and sweet potato in it. Close the lid and seal the valve. Turn it on at high manual for 10 minutes. Once done let the pressure release on its own. Open the lid and drain the water. Microwave – in a microwavable bowl, add water and sweet potato. Microwave at high for 5 minutes. Take it out and turn the potato to the other side. Microwave again for another 5 minutes. Pause and check its softness. Or else microwave for another 5 minutes. Once done, take it out and drain the water and let it cool.