My mashed potatoes are never as light and fluffy as I’d like. What’s the secret?
Actually, there are three secrets: the right taters, the right technique, and the right tool.
1. The taters: High-starch varieties, such as russet and Idaho, give the fluffiest results because of the way their starch behaves during cooking. The microscopic starch granules in these potatoes’ cells separate and swell as they sponge up moisture that’s naturally present in the potato; as a result, the cooked potatoes’ texture seems dry and fluffy. The starches in medium- or low-starch varieties such as Yukon Gold and red potatoes, on the other hand, tend to stick together, giving them a denser, moister texture that becomes creamy (or even sticky) when mashed.
2. The technique: Dry out the potatoes, and add the fat before the liquid. Waterlogged potatoes will give you a gummy mash, so if you cook the potatoes by peeling and boiling them, then you should return the potatoes to the pan after you’ve drained them and mash them over low heat, letting the potatoes dry out for a few minutes. Or use a cooking method that prevents the potatoes from sopping up too much water in the first place: steaming, for example, or boiling the potatoes whole in their skins. Then, after you’ve mashed them, stir in the butter—the fat will coat the starches and help prevent them from absorbing additional moisture when you add the milk, cream, or other liquid.
3. The tool: Use a ricer, a potato masher, or a food mill, because any tool that you need to plug in (e.g., a food processor or electric mixer) is likely to overwork the potatoes, causing the starch granules to burst, release their sticky contents, and turn your mashed potatoes into a gluey mess.