Soba Salad with Marinated Cucumber and Ponzu

Name: Soba Salad with Marinated Cucumber and Ponzu
Ingredients: 3⁄4 cup cilantro leaves, roughly chopped; 1⁄4 cup plus 2 tbsp. mirin; 1⁄4 cup plus 2 tbsp. rice wine vinegar; 1 tbsp. brown sugar; 1 1⁄2 tsp. fish sauce; 1 English cucumber, sliced 1/8-inch thick; 1 red bell pepper, minced; 1 red Thai chile, thinly sliced; 1 small red onion, thinly sliced; Kosher salt and freshly ground black pepper, to taste; 1 (8-oz.) package dried buckwheat soba noodles; 1 cup soy sauce; 1 tbsp. granulated sugar; 1⁄4 cup toasted sesame oil; 2 tbsp. fresh lemon juice, preferably Meyer; 2 tbsp. bonito flakes (amazon.com); Mint and Thai basil leaves, for garnish