Heat small skillet on medium heat. Add sesame seed; cook and stir about 2 minutes or until fragrant. Immediately pour out of hot pan to avoid over-toasting
Cook spaghetti as directed on package. Meanwhile, mix peanut butter, soy sauce, vinegar, sesame oil, sugar, ginger and red pepper in large bowl with wire whisk until smooth. Stir in carrots and sesame seed
Drain spaghetti, reserving 1/4 cup of the cooking water. Add spaghetti and water to carrot mixture; toss to coat well. Sprinkle with green onions. Serve warm