In a large stockpot, combine the whole chicken, halved onion, peeled garlic cloves, green onion, and black peppercorns. Pour in approximately 4 liters of water. Bring to a boil and cover it. Allow to simmer for 25 minutes.

Carefully remove the chicken from the pot and allow it to cool. Remove the meat from the bones, shredding it into bite-sized pieces.

Discard the cooked vegetables, keeping the broth. Return the chicken bones to the pot and let simmer on low heat for another 30 minutes.

Strain the broth using a fine mesh strainer. Season with salt and pepper to taste.

In a mixing bowl, combine all-purpose flour, potato starch, and salt. Gradually add water to form a smooth dough. Knead for 10-15 minutes.

After resting for 1 hour, roll out the dough and cut into noodles. Toss in flour to prevent sticking.

Bring broth to a gentle boil, add shredded chicken and noodles, cooking for 3-4 minutes until noodles are tender. Garnish with chopped green onions and serve hot.