How to perfectly bake Murasaki sweet potatoes with white flesh and red/purple skins, which are also known as Japanese sweet potatoes, Korean yams, Satsumaimo and red kūmara. Nutty, mildly sweet and creamy, these sweet potatoes are absolutely delicious!
Starchy and fluffy, with a chestnut-like flavor, the flavor and texture of Murasaki sweet potatoes are sometimes described as a cross between Russet potatoes and orange sweet potatoes.
Baking them brings out their sweetness, infusing them with hints of brown sugar, caramel and molasses. If you love potatoes, you have to give these a try.
🧄 Ingredient notes
- Sweet potatoes - with purple-red skin and white flesh, these sweet potatoes are called by a variety of names, including: Murasaki sweet potatoes, Japanese sweet potatoes, Korean yams, Satsumaimo and red kūmara. In the United States, look for them at Trader Joe's, H-Mart or Whole Foods. Some farmer's markets may have them. Check Asian grocery stores and don't be scared off by different names. At H-Mart in Houston, they are labeled as "Korean yams". If they look like the picture above and have white flesh inside, you've found them!
📋 Substitutions and variations
Here are some suitable substitutions, if you can't find Murasaki sweet potatoes
- Sweet potatoes - I've listed where to find these in the previous section, so hopefully you can get them somewhere. If not, instead of Murasaki sweet potatoes, use other sweet potatoes you enjoy for this baked sweet potato recipe. You may have to adjust the cooking time, as orange-flesh sweet potatoes don't take as long to cook.
Here are some variations and alternate ways of cooking these Japanese sweet potatoes:
- Steamed - these sweet potatoes can be steamed until tender in the Instant Pot, stovetop or microwave. Here's a step by step how to steam Japanese sweet potatoes in the Instant Pot.
- Baked on Grill or Outdoor Oven - cover in tin foil and bake on an outdoor grill, barbeque pit, smoker or campfire until squishy and tender. In New Zealand, these are traditionally cooked in a hangi, an underground oven, which gives them a lovely smoky taste. Here's a tutorial on how to grill whole Murasaki sweet potatoes outdoors.
- Air Fryer Japanese Sweet Potato Fries - cut into fries, season and air fry until tender.
Step by step instructions for how to perfectly bake Korean yams.
Preheat oven to 400ºF / 205ºC. Wash sweet potatoes, cut away any bad spots and then place on a parchment lined baking sheet.
Poke 3-4 holes in each sweet potato/yam with a knife or fork, so the steam can vent. If you don't do this, they can explode in the oven, which can be a huge mess to clean up!
I would consider these medium sweet potatoes, you can tell the size from this photo. It is almost as long as my hand. If you're using sweet potatoes much smaller than this, reduce the cooking time by 15 minutes. If you are using sweet potatoes much larger than this, increase the cooking time by 15-30 minutes, depending on the size. For extra large sweet potatoes, you can cut them in half to reduce the baking time.
Place sheet pan in oven and bake for 45-60 minutes. They are done when you poke them with a fork and it goes in really easily.
Do a "squish test"! Also check them by wearing oven safe gloves and gently squeezing the sweet potato. If it's squishy and gives easily like soft clay, then it's done.
Allow baked yams to cool on the counter, before storing them in the refrigerator.
Bake them long enough that they are this texture inside and squishy and tender.
Enjoy hot by cutting them open, fluffing them with a fork and sprinkling with kosher salt and everything bagel seasoning.
🧯 Food safety
- Wash hands with soap and water before cooking
- Don't leave food sitting out at room temperature for extended periods
- Never leave cooking food unattended
- Always have good ventilation when using a gas oven or stove
⭐️ Expert tips
- Japanese sweet potatoes take a long time to cook! Don't take them out of the oven until you've done the squish test and they are very tender.
- Don't skip the step to poke holes in the potatoes for venting. I had one explode once!
- Baking sheet - I like using commercial half sheet pans, since they are a standardized size and practically indestructible since they are made for commercial kitchens
- Parchment paper - I buy parchment paper in half sheet size, so I don't have to worry with it rolling and unrolling
- Oven mitts - You'll need some heat-proof oven mitts when doing the "squish test" to make sure your sweet potatoes are done
🥡 Make ahead and storage tips
Allow to cool at room temperature for about 30-60 minutes before refrigerating. Store the baked sweet potatoes in a container or bag in the refrigerator. Will keep up to 5 days.
These ingredients stand up well to freezing for up to 3 months.
👨👩👦👦 Serving suggestions
Murasaki sweet potatoes are versatile and can be served with all kinds of meals. In our plant-based, vegan household, we eat them with steamed broccoli, as snacks (literally just grab one out of the fridge and eat it) and as a stand-in for regular sweet potatoes.
Murasaki sweet potatoes (aka Japanese sweet potatoes, Korean yams, red kūmara) taste mildly sweet, nutty, with notes of chestnut, brown sugar, molasses and caramel. Their texture is starchy, fluffy and moist when baked whole.
Yes, you can. The skin is edible, but can be a little tough sometimes. It is more tender if the sweet potatoes are steamed or boiled rather than baked.
Most likely, you didn't bake them long enough. Japanese sweet potatoes require longer baking times than orange sweet potatoes to get tender. Bake medium sweet potatoes for at least 45-60 minutes. If you have larger ones, they could bake for up to 90 minutes to get squishy and tender. Just keep checking on them and do the "squish test" to be sure they're done!
🗺 Cultural influences
These delicious sweet potatoes are found in many places in the world. I won't be able to capture them all here! Since this variety of sweet potato has such a long cultural history in many parts of the world, the various recipes and delicious ways to enjoy them is endless. Research them by these names to find other recipes to enjoy!
In my limited experience and research, they are called by the following names:
- Murasaki sweet potatoes - At Trader Joe's, they are packaged with this name. Murasaki means "purple" in Japanese. Although these have a Japanese name, they were cultivated to grow well in Louisiana and are grown mostly in California now. They are very similar to the Kotobuki variety of Japanese sweet potatoes.
- Japanese sweet potatoes - They are commonly called this online and in cooking shows. This variety is similar to Kotobuki sweet potatoes grown in Japan.
- Satsumaimo - this is the Japanese word for sweet potato, to my knowledge
- Korean yams or sweet potatoes - Goguma (고구마) means sweet potato in Korean. The most popular is bam goguma (밤고구마) and mul goguma (물고구마), which is the variety pictured here in this recipe.
- Kūmara - sweet potatoes in general are called kūmara in New Zealand. The murasaki sweet potatoes this post is about are called "red kūmara" or Owairaka Red.
This recipe is inspired by food experiences in my diverse hometown of Houston, Texas and by the strong cultural influences of my family and friends from New Zealand and Japan. See About for more information on my cultural influences and how I attribute recipes.
💜 More recipes you'll love
If you love this baked murasaki sweet potato recipe, check out these other plant-based potato recipes!
Perfect Baked Murasaki Sweet Potatoes (Korean Yam, Satsumaimo, Red Kūmara)
- 3 pounds murasaki sweet potatoes washed
- Preheat oven to 400° F. Add washed sweet potatoes to a sheet pan. Lining the pan with parchment paper is optional, but it helps them not stick.3 pounds murasaki sweet potatoes
- Poke 3-4 holes in each sweet potato/yam with a knife or fork, so the steam can vent. If you don't do this, they can explode in the oven, which can be a huge mess to clean up!
- Place sheet pan in oven and bake for 45-60 minutes. If your yams are really big, they may need longer. They are done when you poke them with a fork and it goes in really easily. Also check them by wearing oven safe gloves and gently squeezing the sweet potato. If it's squishy, then it's done.
- When they are done, remove from the oven and allow to cool slightly before eating. Sprinkle with salt, if desired. Allow the potatoes to cool before storing in the refrigerator. They will keep in the refrigerator for up to 5 days and in the freezer for up to 3 months.