Step 1
Slice the sweet potato into about 1/2-inch (1.5 cm) thick rounds and soak in water for about 10 minutes.
Step 2
Arrange the sweet potato pieces on a microwave-safe dish while still slightly wet. Sprinkle Kayanoya Original Dashi Stock Powder evenly on top, add 2 tablespoons of water, cover with plastic wrap, and microwave on medium (600W) for about 6 minutes.
Step 3
While still warm, transfer potatoes to a serving dish and top with butter.