Bring a large pot of water to the boil over high heat for the udon noodles, salt heavily and cook per the package’s instructions (usually about 10 minutes). Once done cooking reserve 1 cup of the cooking water, drain the noodles, rinse with cold water for several minutes, shaking all the while, and set aside.
Pick up the grated ginger in your hand and squeeze it of it's juices into the noodle water. Add the soy sauce, and sugar, stir to combine, and set aside.
When the noodles go into the water, begin to heat the vegetable oil, chili, garlic and the sliced whites of the green onions together in a 4 – 6 quart pot over low heat until they just become fragrant – about 2 minutes.
Chop the leafy tops of the gai lan and trim the very bottoms off the stalks. Slice the stalks into ¼” thick slices and drop into the warm oil. Stir to combine and crank the heat to high.
Once it starts to sizzle after a minute or two pour in the turkey stock and the noodle-water. Cover and bring to a boil.
Chop the leaves of the gai lan into bite-sized pieces and, once the soup is boiling, drop them into it. They just need a mere minute to soften slightly.
Distribute the noodles among four large soup bowls. Ladle the soup on top of the noodles, scatter with the sliced greens of the scallions and cilantro and serve.
If you're using regular, full-sodium soy sauce start with 2 tablespoons and increase from there to suit your tastes. If you're using low sodium soy sauce you may find you need a little more--kind of defeats the purpose if you ask me but...