Roast up these miso butter Japanese sweet potatoes for a delightfully heartwarming (and umami filled!) side dish.
Want to make it lower carb? Turn them into a resistant starch by refrigerating overnight. You know, to improve their digestibility and lower the carb count naturally.
Miso Butter Japanese Sweet Potatoes 🍠
turned into a resistant starch!
If you’ve never had Japanese sweet potatoes you’re in for a treat: lightly sweet and with a dry flesh like its orange counter parts, these guys are often described as a rather chestnut-like in taste.
Either way, slathering with miso butter aplenty is the way to go. For not only is miso paste packed with nutrients (notably vitamins B12 & K), but it also packs a mighty umami punch… you know, making these totally addictive and finger-licking-good.
But what is a resistant starch?
In case some of you are first coming across this term, its a type of carb that resists digestion in the small intestine and subsequently ferments in the large intestine (you know, acting as a legit prebiotic fiber!).
And all you need to do is simply allow your potatoes to cool (after cooking them in any manner your heart desires), refrigerating them overnight and reheating them. Yup, thats it! Though it appears that the longer you refrigerate for (say even up to 4 days?), the greater amount of resistant starch you end up with.
Though in the end how much resistant starch exactly you end up with is unclear, but according to reputable internet sources (say Johns Hopkins) and reputable people who monitor their glucose constantly (say @gluclosegoddess) enough to lower your GI response substantially and (vip!) provide a myriad of nutritional benefits.
p.s. it also appears from consistent feedback that sweet potatoes (including Japanese ones) result in even lower GI spikes than regular potatoes once turned into a resistant starch.
p.p.s. I’m talking about GI spikes as low as those of fully keto meals
p.p.p.s. this isn’t medical advice 😉
The benefits of resistant starches
Starting with this 2017 study, it appears that consuming a moderate amount (think a normal ‘side dish’ serving, don’t overthink it) made peeps feel more satiated and for longer, improving overall insulin sensitivity.
Which in turn is also tied to all the goodness that resistant starches do for your gut. As keep in mind that a healthy gut bacteria can improve glycemic control and, needless to say, is key to our overall health.
So who knew huh? That perhaps we don’t quite need to see all carbs as the enemy, we just need to learn to prepare (and consume them) the right way.
Looking for more resistant starch recipes? My crispy potatoes are another winning side.

(Resistant Starch!) Miso Butter Japanese Sweet Potatoes 🍠
Ingredients
- 2 large Japanese sweet potatoes halved
- extra virgin olive oil as needed
- kosher salt to taste
- 4 tablespoons unsalted butter softened
- 1 tablespoon miso paste preferably light
- 2 tablespoons finely chopped scallions to garnish!
Instructions
- Preheat oven to 400°F/200°C.
- Add Japanese sweet potatoes to a baking dish, drizzle generously with olive oil (make sure the skin is nice 'n coated!) and season with salt to taste. Roast for 45-60 minutes, until golden and crisp, tossing them about half way through.
- Turning them into a resistant starch? Set aside, cool completely and refrigerate overnight. You'll want to reheat them again at 400°F/200°C for 10-15 minutes.
- Mix the miso paste with the unsalted butter and smear half of it on the freshly baked potatoes, garnish with fresh scallions and serve right away with additional miso butter on the side!
- Store in an airtight container in the fridge for up to five days.
Simply I appreciate your hard work! In Sydney, we can buy purple sweet potatoes to give a different dimension to the food. Tine bit healthier.
Aww thank you Judy, I appreciate you too! Thank you for reading and taking the time to write. I also love purple sweet potatoes- so good mixed with chorizo for a breakfast hash 🤌🏼🥰
OH MY YUMMMM. I love this idea! We eat tons of these but never thought of incorporating miso or making them a resistant starch. Leave it to you Paola.
🫡
Dear Paola,
I always wait for your new recipe.
Thank you very much for featuring “Japanese Sweet Potatoes” this time!!
I am from Tokyo, Japan and I have been living in Los Angeles for long time.
Every autumn, sweet potatoes recipes are regular item. However, I really want to tell anybody that Japanese sweet potatoes are way better than regular sweet potatoes (the inside is orange one). The orange one is too watery, but Japanese sweet potatoes’ texture are more rich and thicker. ( Yes, chestnuts like)
Miso is good for your guts health. So these combinations of recipe is sure to good for autumn menu.
Thank you and wishing you for your great life now and future!
Keiko I only discovered Japanese sweet potatoes while living in LA a couple years back- and you are indeed correct that they’re so much better than the regular orange yams (which I also love!).
While I don’t consider myself knowledgeable at all about real Japanese cuisine, I do find so many of your ingredients to be so delicious (and like you said, good for your gut) that I try to incorporate them in my cooking (say, a touch of miso also adds so much umami to bolognese). Thank you for stopping by 😌
I saw your other post on starch resistant potatoes, and just wanted to say THANK YOU for finding a way to incorporate potatoes in a healthy diet!! I appreciate this so much!
Awww my pleasure! I’ve really enjoyed broadening my diet a lot these past two years, and natural fermentation of foods really has improved my digestion (and enjoyment?!) tenfold. As Keiko commented, I can’t recommend Japanese sweet potatoes enough 🤌🏼