Soba Noodle Salad

Name: Soba Noodle Salad
Ingredients: 1/4 cup Dashi or defatted chicken stock; 2 tablespoons low-sodium soy sauce; 1/4 cup rice vinegar; 1 tablespoon sugar; 1 teaspoon Asian sesame oil; 7 ounces dried soba noodles; 1/2 or so cup finely julienned daikon or breakfast radishes; 1 cup daikon radish sprouts, loosely packed; 1 small onion, cut in half, thinly sliced, rinsed, and drained; 2 tablespoons finely chopped green onion; 1 tablespoon sesame seeds, toasted; Japanese seven-spice powder, to taste (optional)