In a mixing bowl, combine the chicken, soy sauce, and sesame oil, and set aside.  In a separate bowl, combine chili paste, garlic, ginger, and peanut butter.

Heat 1 tbsp of chili oil in a pot or saucepan, then add the chicken and brown.  Add the peanut butter and paste mixture to the chicken and saute until browned, about 2 minutes, then stir in the vinegar and deglaze your pan.  Add the chicken stock to the meat, cover, and bring to a simmer for 10 minutes.

While you wait for the broth and meat to come to a simmer, bring another pot of water up to a boil.  Prepare your noodles per package instructions.  Strain your noodles and divide into two bowls, then add meat and broth.  Top with chopped green onion and a drizzle of chili oil if desired.