Cook soba as package directs. Drain, cool, and pat dry with towels.
Mix soy sauce, mirin, vinegar, sesame oil, and sugar in a small bowl.
Combine noodles and vegetables in a large serving bowl. Pour half the dressing over noodles, tossing well to coat. Serve with remaining dressing on the side.
Note: Nutritional analysis is per 1-cup serving without extra dressing.