Step 1

Place the sesame seeds in a dry skillet over medium heat and toast until lightly browned, 2 to 3 minutes. Remove from the heat and set aside.

Step 2

Cook the chicken. In a medium skillet, bring the chicken stock to a simmer over medium-high heat. Submerge the chicken breasts in the stock, then reduce the heat to low and poach until the meat is completely cooked through and the internal temperature in the thickest part of the chicken breast registers 165 degrees F on a meat thermometer, 8 to 10 minutes. Transfer the chicken to a cutting board and let rest for 5 to 10 minutes. Use a sharp knife to cut the meat into 1/4-inch-thick slices. Set aside. Let the chicken stock cool and reserve for another use.

Step 3

Make the pasta. In a medium pot, bring 4 quarts of water to a boil over medium-high heat. Line a sheet pan with a clean kitchen towel and set aside. Season the water with salt until it tastes like sea water. Plunge the pasta in the water and cook until cooked but still chewy (“al dente”), 4 to 6 minutes. Place a colander in the sink. Reserve a little pasta water, then drain the pasta thoroughly. Shake the colander a few times to remove excess water. Spread the pasta on the towel so it cools more quickly. Gently use a second towel to cover and pat the pasta dry. (Removing the excess moisture assures that the sauce will have a full flavor effect on the noodles.)

Step 4

Make the sauce. In a large bowl, combine the hoisin sauce, soy sauce, ginger, sesame oil, vinegar and hot sauce. Adjust the seasonings. Stir in half of the scallions. Set aside.

Step 5

Add the pasta to the sauce and toss to coat evenly. Add some of the reserved water if necessary. Transfer the pasta and sauce to a large serving bowl. Set aside.

Step 6

Arrange the chicken on top of the pasta. Top the pasta with the reserved sesame seeds and remaining scallions.