If you're making a dish as important as mashed potatoes for the holidays, you'll definitely want to get them right. Think fluffy, creamy, and indulgent — never pasty, sticky, or, worst of all, gluey.
It all starts by selecting your potato: either one high in starch, like a tough-skinned russet, or waxy (like a thin-skinned, yellow potato). My personal favorite are Yukon Golds, which have a buttery flavor and creamy consistency. Peel them prior to cooking, since otherwise they'll be too hot to handle. Boil them until soft but not yet dissolving in the pot. Once cooked, steam off any remaining moisture completely, as they need to be as dry as possible before mashing.
Now for the important part. To avoid a gummy, overstarched mess, mash the potatoes while they're dry but still hot, and don't use a food processor or a blender; these appliances tend to overmash the potatoes, creating an undesirably starchy consistency. If you've already gone too far with your food processor and you don't have time to fix the gluey mess, transform it into a gratin instead: spread a thin layer across a baking dish; top with butter, cheese, and breadcrumbs; and bake to form a crispy top.