Zaru Soba (Cold Soba Noodles)

Bahan-bahan (4 porsi)

• ¼ cup sake
• ½ cup soy sauce
• ½ cup mirin ((plus 1 Tbsp, to taste))
• 1 piece kombu (dried kelp) ((1 x 1 inch, 2.5 x 2.5 cm per piece))
• ½ –1 cup katsuobushi (dried bonito flakes) ((packed; if you like a more intense flavor, use the larger amount))
• 14 oz dried soba noodles (buckwheat noodles) ((3.5 oz, 100 g per serving))
• shredded nori seaweed
• 6 Tbsp mentsuyu (concentrated noodle soup base)
• 1 ⅛ cups iced water
• 2 g reen onions/scallions
• wasabi ((optional))