Most roasted sweet potato recipes begin by heating the oven before the pan goes anywhere near it. I skip that step when I want slices with soft centers and deeply browned edges.
The sweet potatoes go into a cold oven under a tight layer of foil. Only then do I set the temperature to 425°F. The gradual rise in heat gives the thick slices time to soften before the foil comes off and the surfaces begin to brown.
I Cut the Sweet Potatoes Into Thick Rounds
For this method, I use about 3 pounds of sweet potatoes and cut them into 1/2-inch-thick rounds. Keeping the slices close to the same thickness helps them cook at roughly the same rate.
I toss the rounds with 2 tablespoons of olive oil, 1 teaspoon of salt, and 1 teaspoon of pepper. Each piece needs a light coating of oil, including the flat surfaces that will sit against the pan.
The Pan Goes Into the Oven While It’s Still Cold
I line an 18-by-13-inch baking pan with parchment paper and arrange the sweet potatoes in a single layer. Overlapping the slices would trap moisture between them and interfere with browning later.
Next comes the unusual part. I cover the entire pan tightly with foil, put it into the cold oven, and set the temperature to 425°F.
The sweet potatoes stay covered for 30 minutes as the oven heats. During this first stage, the enclosed pan holds in moisture while the centers begin to soften.
I Remove the Foil Before Trying to Crisp Them
After 30 minutes, I take the pan out and carefully remove the foil. At this point, I’m not expecting the sweet potatoes to look crisp yet. The first stage was about getting the interiors tender.
I return the uncovered pan to the oven for another 15 to 25 minutes. With the foil gone, moisture can escape and the bottoms sitting against the hot pan begin developing golden brown edges.
There is no need to keep moving the slices around. Leaving them in contact with the pan gives those flat surfaces time to brown.
Flipping Gives Both Sides Time Against the Hot Pan
Once the bottoms are well browned, I flip every round with a thin metal spatula. The paler side now gets direct contact with the pan.
For a slightly sweeter finish, I sprinkle about 2 teaspoons of brown sugar over the sweet potatoes at this point. It isn’t necessary for the method, so I leave it out when I want the natural sweetness of the potatoes to dominate.
The pan goes back into the oven for another 18 to 22 minutes, until the second side develops its own browned edges.
The Cold Start Does Two Different Jobs
Starting with a cold oven might sound backwards for a food I’m trying to crisp, but the crisping doesn’t happen during the cold stage.
The covered cold start gives the thick sweet potato slices time to cook through. Once the oven is hot and the foil comes off, the method changes from trapping moisture to driving it away and browning the exposed surfaces.
That combination is what I’m after: tender sweet potato through the center with darker, caramelized areas around both sides.
I Give Them a Few Minutes Before Serving
I let the finished sweet potatoes sit for 5 to 10 minutes before transferring them to a platter. They are good alongside roasted meat, chicken, grain bowls, or other vegetables, but they can also stand on their own as a simple side.
Leftovers keep in an airtight container in the refrigerator for 3 to 4 days. The edges will soften during storage, so I reheat them in a 400°F oven for 8 to 10 minutes rather than using the microwave when I want some of that crisp texture back.
