The starchier, the better
You only need three ingredients to make crispy hash browns: oil, salt, and potatoes. But that's exactly why it's so important to use the best type of potato to make hash browns, especially if you're serious about making crispy hash browns. There are, after all, so many different potatoes in the supermarket as to be overwhelming. But resist the urge to grab just whatever potato is right there in front of you. That's because different potatoes have different compositions of water and starch, and picking the right potato can be the difference between slogging through a soggy, shredded mass of potatoes and biting into a crispy, crunchy hash brown. So what's the best potato for crispy hash browns?
Well, as Harold McGee writes in On Food and Cooking: The Science and Lore of the Kitchen, there are two types of potatoes: waxy and mealy. Mealy potatoes—like "russets, blue and purple varieties, Russian and banana fingerlings," explains McGee—have a higher starch content and lower water content, so they get dry and fluffy when cooked. Think of the texture of French fries: golden on the outside, soft on the inside.
Waxy potatoes, on the other hand, have a "solid, dense, moist texture" due to neighboring cells that stick together when cooked, and that "holds them together in intact pieces for gratins, potato cakes, and salads," writes McGee. Waxy potatoes are the ones that hold their shape the best after being cooked, the kind of potato you'd want in a potato salad.
So waxy potatoes, like Yukon Golds, are better if you want to ensure your hash browns stick together. But if you want crispy hash browns, grab some starchy potatoes, like Russets. Sure, there's a higher chance that the patty will fall apart than if you used waxy potatoes, but the final crisp will be worth it.
And pro tip? Even if you use the starchiest potatoes, like Russets or Idaho potatoes, you still want to make sure you squeeze out the excess liquid after you shred them up and before dropping them into the pan. That way you can make your hash browns are really as crispy as possible, and there's really not much better than that.