Bring a large pot of water to a boil. Add the noodles and cook as the label directs. Reserve 1/2 cup cooking water, then drain. Whisk the peanut butter, vinegar, soy sauce, 2 tablespoons water, sesame oil, the carrots and half of the jalapeno in a large bowl. Add the noodles and toss to coat.
Meanwhile, heat the canola oil in a large skillet over medium-high heat. Add the scallion whites, ginger and garlic; cook, stirring, until golden, about 2 minutes. Add the turkey and cook, breaking up the meat with a wooden spoon, until browned, about 5 minutes.
Transfer the turkey mixture to the bowl with the noodles. Add half of the scallion greens and cilantro and toss to coat, adding enough of the reserved pasta water to loosen. Serve topped with the remaining jalapeno, scallion greens and cilantro.