I grew up thinking that mashed potatoes came from the dehydrated flakes in a box. When I finally made my own from scratch, the result was such a revelation that I haven't looked back since.
But transforming a potato into the delicious, comforting magic of mashed potatoes really starts at the grocery store. You need to pick the right potato so you end up with light, fluffy mashed potatoes.
Choose Starchy Potatoes for the Fluffiest Potatoes
There are three basic categories of potatoes: starchy, waxy, and in-between. If you want your potatoes to stay intact during the cooking process, like for potato salad, you want to choose flavorful, waxy potatoes, which have the least amount of starch. In-between potatoes, like Yukon Golds, have a medium starch content and are good all-purpose potatoes to have around if you're not sure what you're going to do with them when you buy them.
But for mashing? Starchy is the only way to go. High-starch, thick-skinned potatoes, like Russets, fall apart during the cooking process, mash up light and fluffy, and absorb butter and cream like a dream. Mashing the other types of potatoes will result in a gummy, gluey texture.
Most potatoes in the grocery store are not high-starch potatoes; there is usually a wider variety of waxy or all-purpose potatoes. The only high-starch potatoes will probably be labeled as Russet, or perhaps Idaho or bakers. In some places you may also find Katahdin potatoes.
The best potatoes for mashed potatoes are high-starch potatoes. Look for Russet or Katahdin potatoes.
If Flavor Matters
Starchy Russets are the most mildly flavored potatoes, but some people prefer more flavorful potatoes. If flavor matters to you just as much as texture, do this instead: Make your mashed potatoes with half Russets and half Yukon Golds for the best of both worlds. This blend will yield a nice potato flavor, but still have a light, delicate texture.
Learn How to Make Mashed Potatoes: How to Make the Best Mashed Potatoes