In a blender or food processor, combine the peanut butter, soy sauce, sugar, Worcestershire sauce, sesame oil, rice vinegar, ginger, garlic, and sriracha and pulse to combine. Add the water and process until smooth. Taste, and add salt, if needed.
Transfer the sauce to a jar or lidded container and refrigerate for at least 1 hour (but it’s the best if it’s refrigerated overnight).
When ready to prepare, bring a large pot of water to a boil and salt generously. Add the spaghetti noodles and cook until al dente. Drain, and return to the pot or place in a large bowl. Add the vegetable oil and toss to coat.
Pour the prepared peanut sauce over the noodles and toss until the noodles are coated with the sauce. Add in half of the green onions and half of the cilantro and stir to combine.
Serve topped with the remaining green onions, cilantro, and sesame seeds.
