Cook the spaghetti according to the package instructions.
Just before the pasta is done, add the bean sprouts and snow peas to the pot. Cook for 30 seconds, then drain everything well.
Return the pasta, sprouts, and snow peas to the pot and toss with the sesame oil.
In a large bowl, whisk the peanut butter, soy sauce, vinegar, sugar, scallion, ginger, garlic, and chili sauce with 2 Tbs. of water.
Toss the peanut butter mixture with the spaghetti, sprouts, snow peas, and carrot.