Mashed potatoes are easy: boil some potatoes and mash them. Starting the process with cold water make sure the potatoes cook evenly. Most of the time when you're cooking vegetables, you want to start with hot water. Potatoes, says The Kitchn, are an exception.
Photo by benjgibbs.
While it's best to begin the cooking process with hot water for most vegetables, this isn't the case with potatoes. Adding potatoes to already hot water increases the chances of uneven cooking. The outside of the potato will end up overcooked, while the inside will remain firm and underdone.
After you boil the potatoes, dry them before you mash them for potato perfection. Hit the link for some other mashed potato tips.