Prep vegetables and set aside in bowl.
Boil water for soba noodles.
Meanwhile, add sauce ingredients to small food processor or blender and blend. (In a pinch, you can use a jar with a lid and shake well.) Add water to achieve desired consistency and set aside.
When water is boiling add soba noodles and cook according to package directions. Watch carefully as these can easily boil over.
Rinse cooked noodles well with cold water and drain. You can add a little sesame oil to noodles to keep from sticking together.
Add noodles to bowl.
Pour sauce into bowl and toss well.
Top with scallions and nuts.