If using immediately - heat some oil (peanut oil is best, though vegetable oil works just as well too) in a non-stick pan on medium-high heat.
When well heated, place potstickers on the pan, without overcrowding it (I can fit about 8 on my pan). Heat for about 2 - 3 minutes, until the bottom is lightly browned.
While the pan is hot, add about ¼ cup of water into the pan (the water should sizzle) and immediately cover with a lid. Steam for about 4 minutes.
Remove the lid (most of the water should have evaporated, if not all), then let the bottom of the potstickers cook for another 1 - 2 minutes, and turn golden brown (darker if you use green potsticker wrappers).