Boil water and prepare noodles according to the package. My soba noodles took only 4 minutes.
While the noodles boil, chop, and steam broccoli to desired tenderness.
In a bowl, whisk together the soy sauce, rice vinegar, sesame oil, brown sugar, peanut butter, ginger, salt, red pepper flakes and sriracha.
Drain noodles and return to pot. Pour peanut sauce over noodles and toss gently to combine.
Add the broccoli and combine.
Dish and top with optional sesame seeds and chopped peanuts.
Note: This is excellent cold, so save any leftovers!