Prepare the poaching liquid. In a medium pot, bring 6½ cups water to a boil. Add ginger slices, green onions, chicken bouillon and salt. Give a quick stir. Add chicken leg and make sure it’s submerged. Cover with a lid. Reduce heat to medium. Once boiling, reduce to a simmer and cook for 10 minutes. Turn off the heat and let the chicken sit for 25 – 35 minutes until cooked through. Poke the chicken meat with a chopstick. It’s cooked through if the juice runs clear. The internal temperature should be between 175˚F – 190˚F.
Once cooked, submerge the chicken leg in an ice bath until cold, about 15 – 20 minutes. Using your hands, remove the skin from the chicken and keep in the ice bath. Shred the chicken meat into thin strips with your hands. Transfer to a medium bowl. Cut the chicken skin into thin strips and transfer to a small bowl. Keep everything in the fridge.
In the meantime, work on the dressing. In a small bowl, stir together sugar, poaching liquid, sesame dressing, soy sauce, rice vinegar, sesame oil and salt until combined. Chill in the fridge.
Rinse and pat dry the cucumber. Cut diagonally into ¼-inch slices, then cut into thin strips. Transfer to a small bowl and keep in the fridge.
Just before serving, get the noodles ready (if using), bring a medium pot of water to a boil. Cook the noodles according to the package instructions. Drain and rinse under cold tap water until cool. Drain again and cut into thin strips if needed.
Get everything out of the fridge. Add half of the dressing into the chicken and toss well. Add the cucumber and toss again.
To assemble, prepare a large serving plate. Place the noodles at the bottom, then chicken and cucumber. Add the chicken skin on top. Drizzle the rest of the dressing on top. Sprinkle with sesame seeds. Serve cold.