Simmering Mashed Potatoes In Milk Isn't Everyone's Cup Of Tea

If executed correctly, simmering potatoes in milk is supposed to make for a flavorful and creamy bowl of mashed potatoes. The theory is that by preserving the starch that potatoes release into the cooking liquid, you can take advantage of its thickening properties to achieve a smooth yet not-too-heavy texture. The potatoes will absorb the starch and the dairy and will become soft and creamy without the necessity of extra butter or heavy cream. Since a video about this method was posted on Christopher Kimball's Milk Street Instagram, many people have chimed in with strong feelings on the matter. Some tried it and loved it, some had doubts from the get-go, but one thing is clear: simmering potatoes in milk isn't everyone's cup of tea.

One bemused user @awlr2, comments "Sorry, my mashed potatoes are always a success the way I cook them in SALTED water! Are you sponsored by the American Dairy Farmers' lobby or something?" Many naysayers worry about the price of dairy, with the "in this economy" trope a recurring comment. Of course, if you're adding less cream or butter at the end, you might argue that you come out even. Some worry about technical difficulties, such as scorching the milk, but others responded that the recipe calls for you to simmer the potatoes, and not boil them. But it seems like one of the biggest problems the doubters have with is the thing Milk Street claims is "liquid gold": the potato starch itself.

"I was under the impression you wanted to get rid of the starch as it causes the mash to be gummy," user @tim_elas says, and they might have a point. It's well known that excessive starch is what usually causes gummy potatoes. This led to some confusion amongst the commenters on this Milk Street post, such as @wilsonchristopherr_, who says, "I like milkstreet and always have, but this does not look good. It looks lumpy and on the edge of being gluey. Not pleasant." 

Normally, when people end up with gluey or gummy potatoes, it's caused by the release of excess starch from over-mixing. With the added starch in the milk, viewers feared that it could end up the same way. To mitigate this problem, mix your potatoes as little as possible to avoid releasing more starch. In the video, the chef is seen gently crushing the very soft potatoes — barely mashing them at all — the idea being that since they're already soft, thick, and milky, that work is already done. Whatever method you use, avoid powered mixers and processors or you'll most certainly gum these bad boys up, and it's not easy to salvage ruined mashed potatoes. If your milk-simmered potatoes still turn out gluey, you might find it best to stick to water, but as many commenters suggested, you can preserve that water to thicken your gravy.