Bring a large pot of water to a boil. Season generously with salt. Add the soba noodles and cook until al dente (just firm to bite). Drain and rinse noodles under cold water. Allow to drain and set aside in a large bowl.
To make dressing: combine all the ingredients in a large bowl.
Pour the dressing over soba noodles. Add the rest of the ingredients, and toss gently. Garnish with more sesame seeds and green onions if desired. Best served cold.