For the sauce: In a large bowl, combine the peanut butter, soy sauce, sugar, sesame oil, white vinegar, minced garlic, 1/3 cup water and hot sauce if using. Stir. Keep adding peanut butter until the desired sauce consistency. Set aside.
For the pasta: Fill large pot halfway with water, add the salt and let the water come to a boil. Add the pasta to boiling water. After 8 to 10 minutes, check for doneness. (Longer boil time will result in softer pasta; shorter boil time will result in more "al dente" pasta.) Remove the pasta from the water and put in serving bowls.
Right before serving, add the sauce to the pasta. Toss until every strand is coated with sauce. Garnish with the sliced vegetables or crushed peanuts. Serve.
The peanut butter sauce will stay fresh for up to a week if stored in an airtight container in your refrigerator. This dish can be served hot or cold.