Q: Between Yukon and Idaho and such recipes are being much more specific about potatoes, namely yukons are being called for. It seems like yukons are moister than others. Is there a reason when to use a certain potato in dishes? If so, then which should go with which dish? Which makes the better mashed or better potato in a stew? I never thought about this until now, and I know that you will be able to help me out with this.
A: I'm going to break potatoes down into two categories, waxy and starchy. Though each varietal will fall somewhere different in the spectrum of flavor and texture.
Waxy potatoes would be ones like new potatoes and fingerlings. Typically smaller specimens with tight thin skin, also their flesh is . . . well. . . waxy. These are tasty potatoes, but because they don't have much starch, they're limited to applications like potato salad. They also make great roasted potatoes, but don't contain enough starch to be used in something like gnocchi. And in methods like a mash they produce a very different texture.
Starchy potatoes tend to be bigger with a little less pronounced flavor. Think of idaho potato (AKA the Russet) which tends to be a little more powdery when cooked. Because of this they produce silkier mashed potatoes, work better in soups and gratins, and work perfectly for gnocchi.
Yukon gold potatoes, thought starchier, exhibit traits from both ends of the spectrum and also pack a ton of recognizable potato flavor. A lot of people (myself included) like them for this reason.
