Chilled Sesame Soba Bowl with Cucumber and Scallions

Name: Chilled Sesame Soba Bowl with Cucumber and Scallions
Ingredients: 1 (12-ounce) English cucumber; 12 ounces uncooked soba noodles; 1/4 cup plus 2 tablespoon sesame oil, divided; 1 teaspoon kosher salt; 6 tablespoons soy sauce; 2 tablespoons agave nectar; 3 tablespoons rice vinegar; 1 tablespoon grated lime zest plus 1/4 cup fresh lime juice (from 2 limes); 1/2 cup white sesame seeds, toasted, plus more for garnish; 2 tablespoons tahini; 1/3 cup thinly sliced scallions, plus more for garnish; Black sesame seeds, toasted, for garnish