Cook the rotini pasta according to package instructions until al dente. Drain and rinse under cold water to cool.
In a large bowl, combine the cooled pasta, red bell pepper, cucumber, carrots, green onions, cilantro, and peanuts.
In a separate bowl, whisk together the peanut butter, soy sauce, rice vinegar, honey, sesame oil, sriracha, and minced garlic until smooth. If the dressing is too thick, add water a little at a time until you reach your desired consistency.
Pour the dressing over the pasta salad and toss well to combine.
Cover and refrigerate for at least 30 minutes to allow the flavors to meld. Serve chilled or at room temperature.