How to Make Hoshi-imoJapanese Dried Sweet Potato: Steam, Slice and Sun-Dry for 2–3 Days

Hoshi-imo, dried sweet potato, is a classic Japanese snack: chewy, sticky and intensely sweet.

Store-bought hoshi-imo is pricey, but it’s easy to make at home. Just cook sweet potatoes slowly, slice them, and dry them in the sun.

Autumn, when temperatures drop and sunny days continue, is the perfect season to make it.

When to make	Autumn to winter, when it’s sunny and the air is dry
Time	Steam, then dry for 2–3 days
Storage	Fridge. Freeze to keep longer

How to make hoshi-imo

We used Beni Azuma, a Japanese sweet potato with purple skin and yellow flesh. Japanese sweet potatoes are sold at many Asian grocery stores outside Japan, sometimes as “satsumaimo” or “Japanese yams”.

Cook them through

Cooking sweet potatoes slowly makes them sweeter. The microwave is faster, but we recommend a steamer or rice cooker.

In a steamer, about 50 minutes. In a rice cooker, use the brown rice setting (about 65 minutes).

They’re done when a skewer goes in easily. Large potatoes need longer.

Peel

Peel them with a bamboo skewer while still hot, taking care not to burn yourself.

Peel a little thickly, shaving off the surface. It gives a neater finish.

Slice

When the sweet potatoes have cooled, slice them lengthwise along the fibers, about 1 cm (⅜ in) thick.

Dry in a net

Pick a stretch of sunny days and lay the slices in a drying net without overlapping. Turn them over partway through so they dry evenly.

Bring them indoors at night.

Day 1

Day 2

Day 3

This time we didn’t steam them quite long enough, and some whitish patches were left. The key to hoshi-imo is to take your time and cook them all the way through.

Done

Dry them for 2–3 days. They’re ready when the surface looks slightly translucent.

Dried too long, they get hard, so check them and stop when they’re as you like them.

For dried sweet potato to use in cooking, see dried sweet potato on our dried vegetables site.