How to Cook Sweet Potatoes: Oven Times, Skin and Storage

Hello lovelies,

sweet potatoes are one of the vegetables that end up in my kitchen almost every week. They are sweet, a little nutty and wonderfully versatile: crispy from the oven, creamy as a mash, golden as a rösti or even as the crust of a quiche.

With Thanksgiving coming up, here is everything you need to know: how long sweet potatoes take in the oven and on the stovetop, whether to peel them, how to store and freeze them, and which of my recipes fits each method.

How do you pick good sweet potatoes?

Look for firm, well-shaped sweet potatoes with clean, smooth skin, and avoid any with soft spots or bruises. That is the advice of both NDSU Extension and Clemson University Extension.

University of Illinois Extension adds that whole sweet potatoes should be large and heavy, and recommends leaving behind any that are wrinkled, have cracks, or have obvious soft spots or mold.

Illinois Extension also points out that sweet potatoes work well in sweet and savory recipes. If you buy them ready to use, read the label. According to Illinois Extension, many canned sweet potatoes are sold in syrup, which means added sugar, while the freezer section has sweet potato fries and plain cubed sweet potatoes.

Should you refrigerate sweet potatoes?

No. Raw sweet potatoes belong somewhere dry and well ventilated, not in the fridge. According to Clemson University Extension, refrigeration temperatures can cause dark spots and off-flavors.

How long they keep depends on where you store them. The NDSU Extension vegetable storage chart gives 3 to 4 months in a dry, well-ventilated place. University of Illinois Extension gives a shorter time: stored whole at room temperature in a dark, cool place, they may last up to a month.

Nebraska Extension is the most cautious: stored in a cool, dark, dry place, use them within two to three weeks, or within a week at room temperature. It also warns that storing them in the refrigerator results in a hard center and an unpleasant taste. Once baked, the spiced sweet potato cubes from my taco recipe keep for 3 days in the fridge and crisp up again in the oven.

Do you need to peel sweet potatoes?

No, you don't have to peel sweet potatoes. The skins are edible, but they can have a bitter flavor, according to University of Illinois Extension. Whether you peel them depends on the dish.

Either way, rinse them first. The Nebraska Extension sweet potato prep tips recommend rinsing sweet potatoes under cool, running water to remove any dirt from the skin and scrubbing them with a vegetable brush if needed. They also say it is not necessary to peel sweet potatoes before cooking them.

Stuffed sweet potatoes are broken open with a spoon after baking, showing the orange flesh and the filling. For mash, soup or rösti I usually peel them.

With or without the skin, cut sweet potatoes as evenly as you can for the oven or the skillet. For the salad with figs and roasted sweet potato slices, slice them evenly and fairly thin, about ½ cm (0.2 inch), so they brown nicely without staying raw inside.

How long do you cook sweet potatoes in the oven?

Sweet potatoes take 40 to 50 minutes at 200 °C (400 °F) until soft, according to Clemson University Extension. Prick the skin first.

The Clemson Extension Sweetpotato Basics fact sheet also gives stovetop and microwave times. The microwave is handy when you only need one sweet potato as a side.

In my experience, cubes and thin slices cook much faster, so how long it takes depends on how you cut them. For my sweet potatoes with a chickpea filling, choose sweet potatoes of about the same size so they are all done at the same time. The filling of chickpeas, bell pepper, onion and garlic is seasoned with dried oregano and paprika, and it is also lovely with 1 handful of spinach wilted in the skillet at the end. Leftovers keep for 2 days in the fridge and crisp up again in the oven. The whole recipe takes 75 minutes.

Cut cubes smaller than you think. In my vegetarian tacos with crispy sweet potato cubes, cubes of around 1.5 cm (about 5/8 inch) turn crisp outside and creamy inside, while larger ones stay floury in the middle. Season them with olive oil, paprika, cumin, salt and pepper, and don't crowd the tray: use two trays rather than one dense layer, otherwise the vegetables steam. The avocado cream gets plenty of lime juice, which keeps it green and at the same time brings the acidity that sweet potatoes need.

Slices can even become a crust. My vegetarian quiche with a crust of sweet potato slices needs no pastry at all. Squeeze the spinach out well after wilting it; that is the most important step for a custard that sets. Well covered, the quiche keeps 3 days in the fridge and tastes good cold too.

Oven-warm sweet potato cubes also go into my colorful salad with quinoa, together with tofu that you toss in starch before baking to make it extra crispy. For the sweet potato risotto, you can roast the sweet potato ahead and set it aside, and my autumn rolls with beetroot tahini dip are filled with sweet potato, Hokkaido pumpkin and tofu.

More recipes with sweet potatoes:

Colorful salad with sweet potato and quinoa

Sweet potato risotto with arugula and dried tomatoes

Autumn rolls with beetroot tahini dip

How do you boil and mash sweet potatoes?

Whole sweet potatoes take 30 to 45 minutes in boiling water, depending on size, according to Clemson University Extension. For a mash that isn't watery, let them steam off in the hot pot for 1 to 2 minutes after draining.

That is exactly what I do for my vegetarian sweet potato mash with light miso, which is ready in 35 minutes. Light miso is mild and keeps the flavor of the sweet potato in the foreground, and plant milk, ground ginger and freshly grated nutmeg round it out. In the fridge the mash keeps well covered for 3 days; reheat it in a pot with a splash of plant milk and stir well.

Sweet potatoes make a great dip, too. For my sweet potato hummus with white beans, white beans make the hummus creamier than chickpeas, and you can save the drained bean liquid for another recipe. Since our kids dip along, I keep both dips mild, but feel free to add more ras el hanout or ginger.

And then there is soup. For my sweet potato soup with fresh orange juice, add the juice toward the end and don't let the soup boil hard afterwards, which keeps the fruity aroma alive. Kept airtight, it lasts about 3 days in the fridge.

My sweet potato pumpkin soup tastes almost better the next day, as the flavors meld overnight; reheat it gently and thin it with a splash of broth if needed. My creamy potato soup also has sweet potato in it, along with potatoes, carrots and celeriac; once blended, it keeps covered for 3 to 4 days in the fridge.

How to cook sweet potatoes in a skillet

In a skillet, grated sweet potato turns into a crispy rösti. In my recipe it is combined with regular potatoes.

My vegetarian rösti made from sweet and regular potatoes comes with cheese and a fried egg. Besides sweet and regular potatoes, onion, paprika and fresh thyme go into it, and the whole recipe takes 70 minutes. Keep the first rösti warm in the oven at 80 °C (176 °F) while the second one fries, so both reach the table at the same time. Leftovers can be fried crisp again in the skillet the next day. It is one of my breakfast recipes.

Can you freeze sweet potatoes?

Yes, but cook them first. According to Clemson University Extension, cook sweet potatoes until fork tender, let them cool, then peel and cut or mash them. Dipping peeled sweet potatoes in lemon juice and water prevents darkening.

For the lemon dip, Clemson uses 120 ml (1/2 cup) lemon juice to about 1 liter (1 quart) of water, for about 5 seconds. For mashed sweet potatoes, it recommends mixing 2 tablespoons of orange or lemon juice into each quart (about 1 liter) of mash before freezing.

You can also freeze finished dishes. Well sealed, my sweet potato pumpkin soup keeps up to 3 months in the freezer, and the sweet potato fennel soup freezes well. The miso mash freezes too; it is a little softer after thawing, and vigorous stirring makes it creamy again. You can also freeze the quiche, but the custard turns a little softer. What freezes well and how long soup lasts is all in my guide to freezing soup and how long it lasts.

Raw vegetables are usually blanched before freezing. Which ones need it and for how long is in my step-by-step guide to blanching and freezing vegetables.

What nutrients are in a sweet potato?

A medium sweet potato contains around 130 calories, 30 g carbohydrates and 5 g fiber, according to University of Illinois Extension. Sweet potatoes also contain vitamin A and potassium, among other vitamins and minerals.

The University of Illinois Extension sweet potato handout also notes that, on their own, sweet potatoes are not a significant source of fat or protein. In my recipes they often come with beans, chickpeas or tofu, as in the hummus, the stuffed sweet potatoes and the quinoa salad.

Sweet potatoes and regular potatoes look alike but are stored differently: regular potatoes do best at 7 to 10 °C (45 to 50 °F) in a dark, well-ventilated spot, according to NDSU Extension. Everything about waxy and starchy varieties is in my guide to waxy and starchy potatoes and green spots.

What can you cook with sweet potatoes?

My sweet potatoes turn into oven dishes, mash, soups, dips and rösti. The table shows 8 of my recipes from this post with the method and one tip from each.

If you are new to sweet potatoes, start with oven cubes: they work in salads and tacos, and the spiced cubes from my taco recipe keep for 3 days in the fridge once baked. Then move on to the quiche with no pastry (75 minutes) or the rösti (70 minutes), which take a little longer. The sweet potato hummus is part of my Christmas menu, too.

Sweet potatoes make life easy: they are uncomplicated and can be cooked in so many ways. If you have a favorite way that is missing here, I would love to hear about it. And if you are planning a holiday menu, my guide to pumpkin varieties, peeling and cooking covers the other big fall favorite. Now it's your turn: how do you like your sweet potatoes best, roasted, mashed or in a soup?

Yours, Verena

Recipes to try

Sweet potatoe pumpkin soup

Creamy potato soup with veggies

Stuffed Pumpkin with Rice, Feta and Pomegranate

Colorful oven vegetables with bulgur