Miso sweet potato is an easy and a delicious way to instantly add new flavor to your roasted sweet potatoes! With just 7 ingredients, this side dish is perfect for everyday as well as the holidays.

The savory miso paste and rich butter make the perfect seasoning for sweet potatoes. Serve them whole or mashed for an easy, flavorful side dish.

Feature image shows a bowl of miso sweet potatoes blended with butter and served in a bowl.

ChihYu’s tips

  • Baking time matters: The biggest difference between Garnet and Japanese sweet potatoes is the baking time. Japanese sweet potatoes are denser, so they need an extra 10-20 minutes in the oven. Make sure to test doneness by inserting a knife—if it goes in easily, they’re ready!
  • Miso butter (compound butter): Miso butter adds a rich, savory flavor. Simply combine the two. For a holiday twist, mix in a tablespoon of maple syrup for a touch of sweetness.
  • Sweet potatoes vs. Japanese sweet potatoes: If using Japanese sweet potatoes, add a splash of milk or extra butter to keep them from being too dry, since they have a denser texture than Garnet sweet potatoes.
  • Size consistency: Choose sweet potatoes of similar size so they cook evenly. Larger potatoes will need more time, so adjusting your bake time is important.
  • Air fryer shortcut: If you’re in a hurry, the air fryer is your best friend—35-45 minutes at 370°F (188°C), and you’ll have perfectly cooked sweet potatoes without needing foil!

Ingredients

The rich butter and savory miso paste are a perfect match for sweet potatoes. It’s a great way to add new flavor and excitement to your dinner table!

Photo shows ingredients needed to make the dish.
  • Garnet sweet potatoes or Japanese sweet potatoes: The star of the dish with natural sweetness and a rich, starchy texture—Garnet is softer and moist, while Japanese sweet potatoes are denser and drier with a chestnut-like flavor. You can use either!
  • Ghee or butter: Adds a creamy richness and enhances the flavor of the miso butter.
  • White miso paste: Brings a savory umami depth that complements the sweet potatoes beautifully.
  • Coarse sea salt
  • Ground black pepper
  • Chopped scallions (garnish): A colorful finishing touch that adds extra flavor and freshness.

Jewel/Garnet potatoes vs. Japanese sweet potatoes

When it comes to preparing and seasoning, you can treat Garnet, Jewel, and Japanese sweet potatoes the same—scrub clean, poke holes, bake, and season with salt and pepper to taste.

The main difference is the baking time and texture.

Garnet sweet potatoes will take about 50 minutes at 400°F (204°C), while Japanese sweet potatoes need an extra 10-20 minutes because they’re denser. If you’re mashing Japanese sweet potatoes, add a splash of milk or extra butter to keep them moist.

How to make miso sweet potato

Roasted sweet potatoes slathered with miso butter make a wonderful side dish to have in your back pocket. Here, you’ll find the baking time, temperature, and tips to ensure your sweet potatoes turn out buttery, creamy, and perfectly sweet every time!

Person demos how to bake sweet potatoes and prepare miso butter.
  1. Preheat the oven: Set it to 400°F (204°C).
  2. Prepare the sweet potatoes: Wash, scrub, and poke holes all over the sweet potatoes with a fork.
  3. Bake/roast: Place on a lined baking sheet. Bake for 50 minutes for Garnet sweet potatoes, or 1 hour for Japanese sweet potatoes, until a knife slides through easily.
  4. Make the miso butter: While the potatoes bake, combine ghee (or butter) with white miso paste in a bowl until smooth.
Photo shows two ways to serve the dish - mashed sweet potatoes or served as a whole.
  1. Two ways to serve:
    • Whole: Slice the baked sweet potatoes open, fluff the flesh with a fork, and smear with miso butter. Season with salt, pepper, and garnish with scallions.
    • Mashed: Scoop out the flesh, blend with 2-3 tbsp of miso butter, salt, and pepper in a food processor until smooth. Adjust seasoning and garnish with scallions.

What else can you do with miso paste

A reader once asked me what to do with a jar of leftover miso paste. I get it—no one wants to spend money on a seasoning just to use it once! Luckily, miso paste lasts a long time in the fridge, and I’m a big fan of using it in all kinds of cooking. Here are more dishes you can make, using miso:

What to serve with miso mashed potatoes

Miso butter whipped mashed potatoes are pure comfort food. Believe it or not, the flavor pairs well with both Western and Asian dishes—just like how soy sauce works across all kinds of foods! Here are some pairing ideas:

More dishes using miso butter

And if you have any extra leftover miso butter, this wonderful compound butter is super versatile. Add it to your next bowl of boiled pasta or sautéed veggies, like I do below—it’ll instantly boost the flavor!

A side close shot shows the creamy and rich texture of miso butter sweet potatoes.
Recipe image shows miso butter mashed sweet potatoes served in a bowl.
5 from 2 votes

Miso sweet potato recipe

Prep Time: 10 minutes
Cook Time: 50 minutes
Total Time: 1 hour
Servings: 8 serving
Author: ChihYu Smith
Looking for a tasty side dish? Try miso sweet potatoes! Savory miso paste and rich butter slathered over roasted sweet potatoes -easy and delicious!
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Ingredients 

  • 6 whole Garnet sweet potatoes, or Japanese sweet potato, about 6.5 to 7 oz. per potato
  • 4 tbsp ghee, or butter at room temperature
  • 2 tbsp white miso paste
  • Sprinkle coarse sea salt, to taste
  • Sprinkle ground black pepper
  • 2-3 bulb chopped scallions, garnish

Instructions 

  • Preheat the oven to 400°F (204°C).

Prepare the sweet potatoes:

  • Wash and scrub the sweet potatoes to remove dirt. Pat them dry. Use a fork to poke holes all over the potatoes.

Bake/roast:

  • Place them on a lined baking sheet. For garnet sweet potatoes, bake for 50 minutes. For Japanese sweet potatoes, bake for 1 hour.
  • The sweet potato is cooked when you can easily insert a knife to the thickest part with little to no resistance. The color will be lightly browned and the flesh will be tender and moist. If not, send them back for 10 more minutes.

Miso butter:

  • Use this time to make the miso butter by combining the ghee and the miso with a fork in a bowl.

Two ways to serve:

  • Serve as a whole: Slice the sweet potatoes open soon out of the oven. Be careful of the hot steam. Fluff the flesh with a fork and add a few teaspoons of miso butter and smear it over. Allow the butter to melt, season with salt and pepper to taste. Garnish with a few sprinkles of scallions.
  • Serve mashed: Scoop out the flesh and transfer to a blender or food processor. Add 2-3 tbsp of miso butter and a sprinkle of salt and pepper. Blend until smooth. Taste and adjust. Transfer to a large serving bowl. Garnish with scallions. Serve hot or warm.
  • Notes on using Japanese sweet potatoes: Japanese sweet potatoes have a denser and drier texture. You can lighten the texture by adding a small amount of olive oil or a splash of milk and blend until your desired consistency.

Notes

  • Air fry: Poke holes all over the sweet potatoes with a fork and place them directly in the air fryer (no foil needed). Air fry at 370°F (188°C) for 35-45 minutes, or until soft.
  • Soy-free option: To keep the dish paleo, swap the miso paste for chickpea miso.
  • Larger potatoes: Bigger potatoes will need more baking time. The time and temperature listed should work for potatoes up to 10 oz (283 gram) each.
  • Size matters: Choose sweet potatoes of similar size to ensure even baking.
  • Short on time? Slice the potatoes in half lengthwise, rub with olive oil, and bake cut-side up for 30 minutes, until tender and lightly browned.
  • Holiday flavor twist: Add 1 tablespoon of maple syrup to the miso butter for a sweeter, festive touch!
  • Miso butter storage: Wrap miso butter in plastic wrap and store in an airtight container in the refrigerator for up to 2 weeks. It can also be frozen for several months.

Nutrition

Serving: 1serving, Calories: 160kcal, Carbohydrates: 25g, Protein: 3g, Fat: 6g, Saturated Fat: 4g, Polyunsaturated Fat: 0.4g, Monounsaturated Fat: 2g, Cholesterol: 14mg, Sodium: 200mg, Potassium: 548mg, Fiber: 4g, Sugar: 8g, Vitamin A: 21799IU, Vitamin C: 22mg, Calcium: 46mg, Iron: 1mg
Course: Side Dish
Cuisine: American, Japanese
Keyword: miso butter sweet potato, miso sweet potato
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