Steps

1. Mince 30g long green onion. 【Tip!】 Mincing helps it combine well with the natto and reduces its pungency.
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2. Pound 1 pack of natto with a knife until it becomes sticky, then transfer to a bowl. 【Tip!】 Pounding the natto makes the grains finer, allowing it to cling better to the somen.
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3. To the bowl with the pounded natto, add 1 serving of natto sauce (from pack), 1 serving of karashi (Japanese mustard), 2 and 1/2 tsp soy sauce, 5 shakes of MSG(Ajinomoto) (MSG), and the minced 30g long green onion.
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4. Next, add 1/2 tbsp sesame oil and 1/2 tbsp rice oil, and mix everything well. 【Tip!】 Combining sesame oil and rice oil helps maintain the aroma of sesame oil while improving how it clings to the natto and reducing any heaviness.
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5. Chill the prepared natto sauce thoroughly in the refrigerator.
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6. Boil plenty of water in a pot and cook 100g somen noodles for 10-20 seconds less than the package instructions.
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7. Thoroughly chill the cooked somen noodles in ice water and squeeze out the excess moisture. 【Tip!】 Squeezing out the water well helps the noodles cling better to the sauce and prevents the flavor from being diluted.
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8. Add the well-drained somen noodles to the chilled natto sauce and mix well to coat.
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9. Arrange the somen noodles in a serving bowl.
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10. Sprinkle bonito flakes (powdered) to taste over the entire dish. 【Tip!】 Adding bonito flakes enhances the aroma and umami. You can also heat katsuobushi in a microwave and then crush it.
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11. Finally, place 1 egg yolk in the center to complete the dish.
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