Spring Chicken Stew

In a 5- to 6-quart slow cooker, whisk together the wine, flour, 1/2 cup water, and 1/2 teaspoon each salt and pepper. Add the carrots, celery, onion, and chicken and toss to combine. Cook, covered, until the chicken is cooked through and easily pulls apart, 5 to 6 hours on low or 3 to 4 hours on high. Twenty-five minutes before serving, prepare the noodles according to package directions. Reserve 1/4 cup of the cooking liquid, drain the noodles, and return them to the pot. Add the oil, mustard, 2 tablespoons of the reserved water and 1/4 teaspoon each salt and pepper and toss to coat (adding more water if the pasta seems dry). Toss with the tarragon. Gently fold the peas into the stew and cook, covered, until heated through, about 2 minutes. Serve over the noodles and sprinkle with additional tarragon, if desired.