Prepare the dipping sauce: In a small saucepan, combine dashi stock, soy sauce, mirin, and sugar. Heat over medium until the sugar dissolves, then set aside to cool.

Cook the soba noodles: Bring a large pot of water to a boil. Add the soba noodles and cook according to package instructions (usually 4-5 minutes).

Drain and rinse: Once cooked, drain the noodles and rinse thoroughly under cold running water to remove excess starch and cool them down.

Prepare the garnishes: Finely chop the green onion, grate the daikon radish (if using), and cut the nori into thin strips.

Serve: Arrange the cold soba noodles on a bamboo mat or plate. Place the dipping sauce in small individual bowls. Garnish with green onions, nori strips, and grated daikon.

Enjoy: To eat, dip the noodles into the sauce and add wasabi to taste if desired. Slurping is encouraged for maximum flavor!