You could say sweet potatoes are made for mashing. With more natural moisture and less starch than white potatoes, they become smooth and creamy without much help from fat or dairy.
There’s just one issue: Because their looser structure allows them to soak up liquid more easily, sweet potatoes get waterlogged as they boil, which dilutes their flavor and requires the cook to add flavor back with extra ingredients.
But adulterating the natural flavors of a sweet potato seems a shame when the tubers have the ability to develop remarkable complexity--. Consider the transformation of a sweet potato as it roasts: As the potato’s pectin breaks down in the oven, the free moisture can escape as steam.
The flavor concentrates as the water evaporates, and you’re left with a creamy, earthy, molasses-y treat. Is it possible to replicate that ultraconcentration in a mash-—without going to the trouble of actually roasting?
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Drive Off Moisture—and Mash at the Same Time
After boiling the sweet potatoes, we stir the slices over medium heat in a dry saucepan. This stirring phase helps break down the potatoes—so you need only whisk in the butter later—and concentrates the potatoes by driving off moisture, which escapes as steam.
After testing different increments of time for this second cook, weighing the saucepan before and after and tasting the results, we found that a 7-minute cook was ideal: It reduced the potatoes’ weight by a notable 12 percent, maximizing their flavor without drying them out and rendering them too dense.
To quickly drive off moisture, I tried microwaving pieces of sweet potato, but this resulted in a leathery, tough mash. Boiling sliced sweet potatoes and then blotting them with paper towels was more promising; the texture was tender and the flavor was intensified.
But the method was time-consuming, and I still felt that the mash could be more robust.
For the most efficient moisture loss, I knew I’d need to introduce more heat. What if I simply returned the boiled potato slices to their pot and cooked them again?
I boiled another batch and then dumped the drained potatoes back into the dry saucepan and turned on the heat, stirring frequently to keep the potatoes from sticking. As I stirred, the potatoes broke down, and I watched as a steady stream of steam escaped the saucepan.
I had cracked the code. When I tasted the potatoes after a few minutes of stirring, they were thickened, creamy, and brimming with earthy sweetness. Now to complete the package: Salt was a must, and I liked the way a few tablespoons of butter enhanced the mash’s earthiness. I wondered if a touch of cream or sweetener could further ramp up the flavor, so I cooked a few batches of the potatoes, adding various levels of cream, white and brown sugar, and maple syrup.
I then called my colleagues in to sample them. The team’s conclusion? All those extras actually detracted from the pure, natural flavor of the mash. While we won’t object to a topping or two (I developed one sweet and one savory option to dress them up), these sweet potatoes can certainly stand on their own.
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