Steps

1. Peel **250g Japanese Yam**, place in a thick plastic bag, seal the bag, and pound until it loses its shape. (Key tip: Using a plastic bag prevents your hands from getting messy.)
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2. Add **1 Egg**, **1 tbsp Potato Starch**, and **1 tsp Dashi granules** to the plastic bag. Knead to break up the egg and mix everything together.
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3. Finely slice **5 Perilla leaves** after removing the stems and cutting them in half lengthwise. Reserve a small amount for topping.
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4. Add the remaining sliced perilla leaves to the plastic bag and knead to incorporate them into the batter.
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5. Lightly oil a frying pan and heat over medium heat.
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6. Cut off a corner of the plastic bag and squeeze the batter onto the heated frying pan. Spread it with a spatula or shake the pan to spread it evenly.
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7. Cover and steam-bake over low heat for **7 minutes**. (Key tip: Slow steaming over low heat allows the batter to puff up and set, resulting in a fluffy texture.)
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8. Carefully slide the cooked side onto a plate by inverting the pan over it. Reshape if necessary and cook until golden brown on both sides. Add more oil if needed.
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9. Once both sides are browned, turn off the heat and transfer to a serving plate.
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10. Optionally, brush or drizzle **Soy Sauce**, **Mentsuyu (Noodle Soup Base)**, or **Soy Sauce Base (Dashi Shoyu)** over the gratin.
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11. Sprinkle **1 pack of Bonito Flakes (Katsuobushi)** over the top, then add the reserved perilla leaves to the center. It's ready!
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