Koppa Mochi (Dried Sweet Potato Rice Cake)
Quick answer
- Total time
- 80 min
- Level
- Hard
- Servings
- 25 servings
- Ingredients
- 6
About this dish
Koppa mochi is an Amakusa rice cake from Kumamoto made by steaming glutinous rice separately from koppa, sweet potato slices that were boiled and sun-dried for storage.
Read more
Both are mashed and pounded together with brown sugar, white sugar, and salt, then pressed into a thick slab to firm. The food grew from island households preserving sweet potatoes for later use. It is sliced and eaten while soft, then grilled or reheated after it hardens. Chewy rice carries the concentrated sweetness and fibers of dried sweet potato, while two sugars keep the cake dense and moist.
Ingredients
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Instructions
Read the steps as a cooking flow: prep, heat, seasoning, doneness control, and finish.
- 1Prep
Wash glutinous rice three times until nearly clear, soak in 4L water under refrigeration for 8 hours, and drain for 30 minutes so its surface is no longer wet.
- 2Control
Rinse 3kg koppa quickly, place in a covered sieve, and rest at room temperature for 6 hours to equalize moisture.
If pieces remain brittle, mist with up to 100ml cold water in small additions.
- 3Step
Line two tiers of a fully steaming steamer with damp cloths and spread rice and koppa separately.
Steam rice for 35 minutes and koppa for 25 minutes, checking that each crushes easily between fingers.
- 4Step
Mash hot koppa in a mochi machine or mortar for 4 minutes, then add steamed rice.
Pound for 10 to 12 minutes until no large potato pieces or separate rice grains remain.
- 5Season
Add brown sugar, white sugar, and salt in three additions, pounding 2 minutes after each until absorbed.
Press into a damp mold 4cm thick, firm at room temperature for 4 hours, and cut into 25 pieces.
Practical Cooking Checks
The cues that matter most while cooking.
- Key technique
- Three kilograms of preserved koppa
- Finish cue
- Add brown sugar, white sugar, and salt in three additions, pounding 2 minutes after each until absorbed.
- Storage and reheating
- Koppa mochi is an Amakusa rice cake from Kumamoto made by steaming glutinous rice separately from koppa, sweet potato slices that were boiled and sun-dried for storage.
Cooking decision evidence
Calculated Charim data and applicable official cooking and food safety guidance.
This recipe
80min, 6 ingredients
Category median
45min, 6 ingredients
Based on 144 recipes
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