First bring a large pot of salted water to boil. Boil noodles according to package directions.
While that’s going on, prepare the dressing.
Make the dressing: Place the garlic and ginger in a blender and pulse to chop them up a bit.
Add the remaining ingredients – sesame oil, rice vinegar, tamari, sriracha, sugar, peanut butter, and water, and puree until it’s completely smooth.
Add a little extra warm water if needed to thin.
When the noodles are ready, run them under cold water to cool completely.
In a large mixing bowl, toss the noodles with the dressing to coat.
To assemble, place a bunch of noodles down the center of a romaine heart, leaving a little bit of space at the top and bottom.
Sprinkle with black sesame seeds.
Tie each heart up with a whole scallion to form a bundle.
