Crispy Smashed Purple Sweet Potatoes with Miso Butter Tips, FAQ & printable recipe

Tips for success

For the crispiest results, use a heavy-duty baking sheet and avoid lining with foil, which can trap steam. Parchment paper works well.

Also, make sure the potatoes are completely dry before smashing — any moisture will hinder browning. If you have time, let the boiled potatoes cool and dry on a wire rack for 10 minutes before smashing.

The miso butter can be made ahead and stored in the refrigerator for up to a week. Let it come to room temperature before using so it's spreadable.

For a spicier kick, add a pinch of chili flakes or a dash of hot sauce to the butter. You can also double the miso butter recipe and use it on roasted vegetables, grilled corn, or steamed rice.

Variations

• Spicy Miso Butter: Add 1/2 teaspoon of gochujang or sriracha to the miso butter for a spicy kick. Reduce the honey slightly to balance the heat. This version pairs well with grilled meats or as a topping for roasted vegetables.
• Herb-Infused Butter: Add 1 tablespoon of finely chopped fresh herbs, such as chives, parsley, or thyme, to the miso butter. The herbs brighten the flavor and add a fresh, aromatic note that complements the earthy potatoes.
• Maple-Miso Glaze: Swap the honey for maple syrup for a deeper, more complex sweetness. The maple flavor pairs beautifully with the miso and adds a subtle smokiness. This version is especially good in the fall.
• Vegan Version: Use vegan butter or olive oil in place of butter. The miso and honey are already vegan, but ensure the butter is plant-based. This version is just as creamy and flavorful, with a slightly different texture.

Storage and make-ahead

Fridge

Store leftovers in an airtight container in the refrigerator for up to 3 days. Reheat in the oven to restore crispiness.

Freezer

Freeze the roasted potatoes in a single layer on a baking sheet, then transfer to a freezer-safe bag for up to 2 months.

Reheat

Reheat in a 400°F (200°C) oven for 5–7 minutes until hot and crispy. Avoid microwaving, which makes them soggy.

Store leftover potatoes in an airtight container in the refrigerator for up to 3 days. Reheat in a 400°F (200°C) oven for 5–7 minutes to restore crispiness. The miso butter can be stored separately in the refrigerator for up to a week.

The potatoes can be boiled and smashed a day ahead. Store them in the refrigerator on a baking sheet, covered, until ready to roast. Brush with oil and season just before roasting. The miso butter can also be made ahead and refrigerated; bring to room temperature before serving.

Serving ideas

Serve these crispy smashed purple sweet potatoes as a standout side dish alongside roasted chicken, grilled steak, or seared fish.

They also work beautifully as a vegetarian main when paired with a simple green salad and a grain like quinoa or farro. The vibrant color makes them a festive addition to holiday tables.

For a casual meal, serve them as a hearty snack or appetizer with a dollop of sour cream or Greek yogurt on the side.

The miso butter is rich, so a light, tangy accompaniment balances the flavors. Garnish with extra sesame seeds and scallions right before serving for a fresh, vibrant finish.

Frequently asked questions

Recipe card

Crispy Smashed Purple Sweet Potatoes with Miso Butter

Prep 15 minCook 35 minTotal 50 minServes 4

Ingredients

• 5 small Japanese purple sweet potatoes
• 2 tbsp olive oil
• 1 tsp sea salt
• 50 g softened butter
• 1 tbsp white miso paste
• 1 tbsp honey
• 1 clove garlic, grated
• Sesame seeds, for sprinkling, to taste
• Scallions, thinly sliced, for garnish, to taste

Instructions

1. Place the Japanese purple sweet potatoes in a large pot and cover with cold water. Bring to a boil over high heat, then reduce to a simmer and cook for 20–25 minutes, until a fork slides easily into the center of a potato. Drain well and let cool for a few minutes until just cool enough to handle.
2. Preheat the oven to 425°F (220°C). Line a baking sheet with parchment paper. Place the boiled potatoes on the sheet, leaving space between each. Use a heavy flat-bottomed glass or a potato masher to gently press down on each potato until it flattens to about 1/2-inch thick. The edges will crack and create lacy, rough edges.
3. Brush the tops of the smashed potatoes with olive oil, making sure to get into the cracks and crevices. Sprinkle evenly with sea salt. Turn the potatoes over and brush the other side with the remaining oil, then season again with a pinch of salt.
4. Roast the potatoes in the preheated oven for 25–30 minutes, flipping halfway through, until the edges are deeply golden, dark, and blistered, and the exterior is crunchy. The interior should remain vibrant violet and tender. Remove from the oven and let rest for 2 minutes.
5. In a small bowl, combine the softened butter, white miso paste, honey, and grated garlic. Mash with a fork until the mixture is creamy, smooth, and well combined. Set aside at room temperature so it stays spreadable.
6. Immediately after the potatoes come out of the oven, place a small dollop of the miso butter on each hot potato. The residual heat will melt the butter, allowing it to seep into every crack and crevice.
7. Sprinkle the potatoes with sesame seeds and thinly sliced scallions. Serve immediately while the potatoes are still crispy and the butter is melted.

Contains: milk, soy, sesame

Estimated nutrition per serving

Calories

280

Protein

3 g

Carbohydrates

45 g

Fat

11 g

Automatic estimate from the ingredient list, not laboratory-verified.