Potatoes and yams
Dried Sweet PotatoParboil, Then Dry: Drying Time and Storage
We dried Japanese sweet potatoes, which have purple skin and pale yellow flesh. Keep the skin on.
Drying boosts their sweetness and aroma. The cut surfaces discolor easily and they have some bitterness, so boil them briefly in salted water before drying.
| Drying time | Storage | |
|---|---|---|
| Dry | 3–4 days | 3 weeks at room temperature (fridge in humid summer) |
Drying times assume drying during the day in sunny weather and bringing them in at night.
How to dry sweet potatoes
- Wash: Scrub the skin well with a brush. Don’t peel.
- Cut: Slice into rounds about 1 cm (⅜ in) thick.
- Boil in salted water: Boil for 5 minutes in water with a pinch of salt. They should still be a little firm, not cooked all the way through.
- Pat dry and dry: Pat dry with paper towels and spread on a basket without overlapping. Put them somewhere sunny and breezy, turn about once a day, and bring in by evening.
Where and when to dry is covered in How to Dry Vegetables, and tools in Tools for Drying Vegetables.
How this differs from hoshi-imo
Hoshi-imo, the dried sweet potato sold as a snack in Japan, is made by steaming whole sweet potatoes until soft, peeling them, cutting them thick and drying them. The method on this page makes dried sweet potato for cooking. To make hoshi-imo, steam a sticky, moist variety (such as Beni Haruka or Silk Sweet) for about an hour, cut into 1 cm (⅜ in) slices, and dry for 3 days to a week. See how to make hoshi-imo on our preserved foods site.
When it’s done
Dry (3–4 days)
It’s done when the rounds have shrunk, the surface has hardened, and they don’t dent when pressed. Sweet potatoes are sugary and the surface tends to get sticky, so keep drying while they still feel moist.
Day by day
Before drying
Day 1
Day 2
Day 3
Storage
- Dry: Put completely dry rounds in a bag or airtight container with a desiccant, and keep somewhere cool and out of direct sun for about 3 weeks. In humid summer weather, keep them in the fridge.
- Frozen: Frozen, they keep 1–2 months.
A white powder may appear on the surface. This is the sweet potato’s sugar crystallizing, not mold. Fuzzy, cotton-like growth, green or black spots, or a bad smell are signs of mold or spoilage; throw it away. More in How to Store Dried Vegetables.
Rehydrating and using it
- Rehydrate: Soak in water for 10 minutes, then boil for about 5 minutes before using.
- Use it dry: Add straight to tonjiru (pork miso soup), miso soup, kenchin-jiru (vegetable and tofu soup) and simmered dishes, and simmer a little longer.
- Good in: Sweet simmered sweet potato, daigaku imo (candied fried sweet potato), mixed rice, salads, tempura.
