Mashed Japanese Sweet Potatoes

My family loves all kinds of mashed potato recipes. You name it, we’ve tried it—from alternative ways of preparing them, such as riced potatoes, to using different types of potatoes for mashed sweet potatoes. That’s why we couldn’t resist making mashed Japanese sweet potatoes when we came across the unusual tubers in the grocery store.

If you’re new to this root vegetable, mashing it is the perfect way to get acquainted with it. Unlike American sweet potatoes, Japanese sweet potatoes have a higher starch content and a fluffier texture. They can be identified by their reddish-purple skin and white-yellow interior. When cooked, they take on a golden hue. They’re mildly sweet and have a slightly nutty flavor, making them excellent for mashing, baking and frying.

What are Japanese sweet potatoes?

Potatoes originated in Central America, and sweet potatoes were brought to Japan in the 1600s. In the 1700s, subjects were encouraged to grow this nutritious vegetable to prevent famine if rice crops failed. Because they grow well in a variety of conditions, sweet potatoes are now grown throughout Japan. They’re used in many different sweet and savory Japanese dishes.

Here’s where things get interesting: The murasaki (which means “purple” in Japanese) variety of Japanese sweet potato that you’ll find in American grocery stores is actually a relatively new variety of potato. It was developed in the early 2000s at the Louisiana State University AgCenter Sweet Potato Research Station. Although they originated in Louisiana, today most murasaki sweet potatoes are grown in California. The potatoes are harvested in late summer and early fall, meaning you’ll most likely find them in your grocery store between September and January.

Ingredients for Mashed Japanese Sweet Potatoes

• Japanese sweet potatoes: You will need 3 to 4 pounds of Japanese sweet potatoes for this recipe. You should be able to find them in most well-stocked grocery stores (they may be labeled “Japanese sweet potatoes” or “murasaki sweet potatoes”). Trader Joe’s commonly stocks them as a seasonal item during the fall and early winter months. Another option would be to check your local Asian grocery store. When selecting Japanese sweet potatoes, look for firm potatoes that have smooth skin with no cracks, soft spots or blemishes.
• Heavy cream: You can’t beat the luscious flavor of heavy cream, but you could substitute half-and-half cream or whole milk if necessary.
• Butter: Butter complements the sweet and nutty flavor of the Japanese sweet potatoes by adding rich flavor.
• Seasonings: The mashed Japanese sweet potatoes are seasoned simply with salt and pepper.

Directions

Step 1: Boil the potatoes

Add the peeled and cubed sweet potatoes to a large pot filled with cold water. Season the water with salt and bring it to a simmer over medium-high heat. Simmer the potatoes for 20 to 25 minutes, or until they’re tender and easily pierced with a fork. Drain the potatoes and set aside.

Editor’s Tip: Because the potatoes oxidize (turn brown) fairly quickly, peel and cube them one at a time. You can prevent this by filling the pot with water first and then adding the potatoes immediately after cubing them.

Step 2: Mash the potatoes

Add the butter and heavy cream to the same pot and heat them over medium-low heat until the butter is melted. Turn off the heat and add the cooked potatoes back into the pot.

Mash the potatoes to your desired consistency with a potato masher. Alternatively, use a hand mixer to whip the potatoes until they’re fluffy. Add more heavy cream if necessary.

Step 3: Season and serve the potatoes

Season the mashed sweet potatoes with additional salt and pepper to taste. Transfer them to a serving dish, top them with a pat of butter and serve them immediately.

Mashed Japanese Sweet Potatoes Variations

• Add a savory note: Stir in a tablespoon of white miso paste to add savory, umami flavor to the sweet potatoes.
• Add more creaminess: For ultra-creamy mashed Japanese sweet potatoes, stir in 2 to 3 tablespoons of sour cream or plain Greek yogurt before mashing.
• Add fresh herbs: Add chopped tarragon, thyme or parsley for a fresh herbal flavor.

How to Store Mashed Japanese Sweet Potatoes

Transfer any leftover mashed Japanese sweet potatoes to an airtight container and store them in the refrigerator for up to four days.

How should you reheat mashed Japanese sweet potatoes?

You can easily reheat Japanese sweet potatoes in the microwave. Transfer them to a microwave-safe dish, cover it and heat the potatoes in 30-second intervals until they’re warmed through, stirring to prevent any hot or cold spots.

Mashed Japanese Sweet Potatoes Tips

What can you serve with mashed Japanese sweet potatoes?

These mildly sweet and creamy mashed Japanese sweet potatoes pair well with everything from savory pork chops and roast chicken to a simple cast-iron steak. Complete the meal with a fresh green salad or roasted vegetable such as roasted green beans or garlic roasted Brussels sprouts.