Thinly slice the bell pepper and scallions. Roughly chop the basil, cilantro, mint, and peanuts.
Cook noodles according to package instructions. Transfer to a serving bowl.
Whisk the lime juice soy sauce, peanut butter, brown sugar, and vegetable oil in a medium bowl until smooth. Pour the dressing over the noodles. (If possible, do this when the noodles are hot – it helps melt the peanut butter, which will still be chunky in the dressing.)
Add the bell pepper , scallions, basil, cilantro, and mint and toss to combine. Season with salt and sprinkle with the peanuts.