One of the most revelatory things I learned while working as a line cook was that restaurant food is, essentially, very good reheated leftovers. Sure, proteins are seared on the spot and crème brûlée is torched to order, but everything else — risotto, pasta, green beans, soups — are made hours and days in advance. As soon as an order is fired (meaning the server tells the kitchen staff to start preparing the salads and steak tartare for table 11), everything is reheated in skillets and sizzler platters in the oven. What does this have to do with potatoes? Right. Those are prepared way in advance too.
Most mornings on the job, I was tasked with peeling pounds and pounds of russets for creamy potatoes. I would then cut the spuds with the largest restaurant-provided chef's knife I could find and transfer them to a 22-quart container, cover them in water, and store the incredibly heavy container in the refrigerator. At that point, they would hang out, uncovered, for a few days until we were running low on mashed potatoes or hand cut French fries and it was time to make more.
The lesson here is not that you should get a job as a line cook, or that you need to invest in a 22-quart vat to get ahead on Thanksgiving prep. No. The lesson here is that you can keep potatoes from turning brown by storing cut potatoes in cold water to slow the oxidation process (aka the thing that makes peeled potatoes turn brown). You probably should keep them covered in an airtight container though. While we did this for Russets, you can also follow this method for Yukon golds, baby red potatoes, sweet potatoes, and even winter squash. Just be sure that the potatoes are fully and completely submerged in water. If the peeled potatoes are exposed to air, they will start to turn color (first a pinkish-red color and then they'll turn dark brown).
This is a brilliant cooking tip that will help you to save time in the kitchen, especially before big dinner parties and holiday feasts. Just be sure to store peeled potatoes in water for no more than 24 hours. After that, the cool refrigerator air will convert the starches in the potatoes to sugar, causing the flavor and texture of the spuds to change. Instead, just start cooking potatoes for a mash, potato salad, or hash browns. But guess what? You can make those in advance, too.