- 3 dried anchovies or 3 tablespoons dried bonito flakes
- 1 small piece konbu (dried kelp), wiped lightly with a dry cloth
- 1 garlic clove, peeled
- 3 tablespoons gochujang (Korean hot pepper paste)
- 2 tablespoons finely grated cucumber
- 2 tablespoons finely grated daikon radish
- 2 tablespoons fresh lime juice
- 1 tablespoon finely grated ginger
- 1 tablespoon low-sodium soy sauce
- 2 teaspoons toasted sesame oil
- 1 1/2 teaspoons sugar
- 1 (7-ounce) package green tea soba noodles
- 1/2 medium cucumber, cut into matchsticks
- Thai or regular basil leaves (for serving)
- Bring anchovies, konbu, garlic, and 1 1/2 cups water to a boil in a medium pot over medium-high, stirring occasionally. Reduce to a simmer, cover, and cook 7 minutes. Pour mixture through a fine-mesh sieve set over a large bowl; discard solids.
- Whisk gochujang, cucumber, radish, lime juice, ginger, soy sauce, sesame oil, sugar, and 1 cup dashi in a medium bowl until well combined. Chill until cold.
- Cook soba noodles in a large pot of boiling salted water, stirring occasionally, until noodles are cooked through but still chewy, 4–6 minutes. Drain and rinse with cold water immediately to stop the cooking process.
- Divide noodles among 2 plates or bowls. Garnish with cucumber matchsticks and Thai basil leaves. Serve with dipping sauce on the side.
- Dashi can be made up to 3 days in advance and refrigerated.