Crispy Smashed Purple Sweet Potatoes with Miso Butter

These crispy smashed Japanese purple sweet potatoes are a stunning twist on the classic smashed potato. Boiled until tender, pressed flat, and roasted at high heat until the edges turn dark, crunchy, and blistered, they offer a satisfying contrast of textures.

A savory-sweet miso butter, made with white miso, honey, and fresh garlic, melts into every crack, coating each bite with umami richness. Finished with sesame seeds and scallions, this dish is as beautiful as it is delicious — perfect for weeknight dinners or holiday spreads.

Purple sweet potatoes, with their vibrant violet flesh and naturally sweet flavor, become something extraordinary when smashed and roasted. The boiling step ensures a creamy interior, while the high-heat roasting creates a crispy, caramelized exterior that's irresistibly crunchy.

The miso butter is the perfect companion: white miso adds savory depth, honey brings sweetness, and garlic provides a pungent kick. This recipe is simple enough for a casual dinner yet impressive enough for entertaining. Serve these potatoes as a standout side dish, and watch them disappear.

Ingredients

Why this recipe works

Boiling the potatoes whole before smashing ensures they cook evenly and stay moist inside. Unlike raw potatoes that can dry out during roasting, boiled potatoes retain their creamy texture while the exposed surfaces crisp up beautifully.

The smashing step increases the surface area, allowing more edges to caramelize and become crunchy, creating that perfect contrast between crispy exterior and tender center.

The high oven temperature of 425°F (220°C) is key to achieving blistered, dark edges without overcooking the interior. The combination of olive oil and sea salt enhances the natural sweetness of the potatoes while promoting browning. The miso butter, applied after roasting, melts into the hot crevices, infusing each bite with a savory-sweet glaze that complements the earthy potato flavor.

Notes and substitutions

Japanese purple sweet potatoes are denser and less moist than orange sweet potatoes, which makes them ideal for smashing. They hold their shape well and have a beautiful violet hue that intensifies when roasted.

If unavailable, regular sweet potatoes or even Yukon Gold potatoes work, though the color and texture will differ. Choose small, uniform potatoes for even cooking and easier smashing.

For the miso butter, use white (shiro) miso for a milder, sweeter flavor. Yellow miso can be substituted but is stronger, so use slightly less. The honey adds a floral sweetness that balances the salty miso. Fresh garlic is essential — pre-minced garlic lacks the same punch. Softened butter is crucial for a smooth mixture; if the butter is too cold, it won't blend evenly.

• Japanese purple sweet potatoes: Regular sweet potatoes or Yukon Gold potatoes for a different color and texture.
• White miso paste: Yellow miso for a stronger flavor; reduce the amount slightly.
• Honey: Maple syrup or agave nectar for a similar sweetness.
• Softened butter: Vegan butter or olive oil for a dairy-free version.

Equipment

• Large pot for boiling
• Baking sheet
• Parchment paper
• Heavy flat-bottomed glass or potato masher
• Pastry brush
• Small bowl for miso butter
• Fork for testing tenderness