Roasted Japanese Sweet Potatoes Recipe
Japanese sweet potatoes have less water and more starch than the orange kind, so a hot oven turns their natural sugars into a deeply caramelized crust while the inside stays dry, dense, and almost chestnut-like instead of watery.
- Prep
- 10 min
- Cook
- 40 min
- Total
- 50 min
- Servings
- 4
Ingredients
- 4 medium (about 2 lbs total) Japanese sweet potatoes (murasaki), scrubbed
- 2 tablespoons neutral oil (avocado or vegetable)
- 3/4 teaspoon kosher salt
- 2 tablespoons unsalted butter, melted
- 1 tablespoon toasted sesame seeds
- 2 whole scallions, thinly sliced
Nutrition per serving
- Calories
- 252
- Protein
- 3g
- Carbs
- 30g
- Fat
- 14g
Based on the recipe as written, one serving. Recalculates if you swap an ingredient above. An estimate only, exact values depend on the specific ingredients used.
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Instructions
- 1Preheat the oven to 425°F (220°C) and set a rack in the lower third. Line a rimmed sheet pan with parchment.
- 2Scrub the sweet potatoes and pat dry. Halve each one lengthwise, then halve again if any are especially thick, so all pieces are roughly the same size.
- 3Toss the pieces with the oil and salt, then arrange them cut-side down on the sheet pan in a single layer, leaving space between pieces.
- 4Roast for 30 minutes without flipping, then check a piece by piercing the thickest part with a knife; it should slide in with almost no resistance.
- 5Continue roasting another 5-10 minutes if needed, until the cut sides are deeply caramelized and slightly sticky at the edges.
- 6Transfer to a platter, brush with the melted butter, and scatter with sesame seeds and scallions before serving hot.
Tips & variations
- Look for Japanese sweet potatoes (sometimes labeled murasaki or satsumaimo) by their dark reddish-purple skin; the flesh inside is pale yellow to white, not orange.
- For extra-crisp edges, soak the cut pieces in cold water for 15 minutes before roasting to rinse off surface starch, then dry thoroughly before oiling.
- A drizzle of soy sauce and a squeeze of lime after roasting works well if serving alongside grilled meat instead of the butter-sesame finish.
- Smaller potatoes can be roasted whole and unpeeled at the same temperature for about 45-55 minutes if halving isn't practical.
Storage & reheating
Store leftover roasted sweet potatoes in an airtight container in the refrigerator for up to 4 days. Reheat cut-side down in a 400°F (205°C) oven or air fryer for 8-10 minutes to recrisp the edges; microwaving works but leaves them soft.
Tips from the Tulo kitchen
- If the skins wrinkle or feel soft before roasting, the potatoes are past their prime; firm, taut skin means a drier, sweeter roast.
- Cutting a small piece off one end before halving helps the potato sit flat on the cutting board and prevents slipping.
FAQ
What's the difference between Japanese sweet potatoes and regular orange sweet potatoes?
Japanese sweet potatoes have dark purple-red skin and pale yellow to white flesh, and they're drier and starchier than orange-fleshed varieties, with a flavor closer to roasted chestnuts than the wetter, more custardy orange kind.
Do I need to peel Japanese sweet potatoes before roasting?
No, the skin is thin and edible once roasted and becomes slightly chewy at the edges; just scrub it well before cutting.
Why did my sweet potatoes come out dry instead of caramelized?
This usually means the oven wasn't hot enough or the pieces were crowded on the pan, which traps steam; 425°F with space between pieces is what produces browning instead of just softening.
Can I air-fry Japanese sweet potatoes instead of using the oven?
Yes. Cut them into 1-inch chunks, toss with oil and salt, and air-fry at 400°F (205°C) for 18-22 minutes, shaking the basket halfway through.
