Trim excess fat from the chicken. Salt each side of the chicken thighs and set aside.
Bring a pot of water to a boil.
While the pot of water is coming up, grab a dutch oven and set it on the stove. Heat up a few tablespoons of oil and sweat down leeks, carrots and celery on medium high heat.
After 4-5 minutes, or when the leeks are becoming translucent, add in stock and bring to a boil.
When stock is up to a boil, lower to a simmer and add in the chicken. Simmer for 15 minutes, or until the chicken is at an internal temp of 180 or higher and can be easily shredded.
While the chicken is cooking, cook noodles to desired doneness, about 12 minutes. Strain the noodles, toss them in oil and lay out on a sheet tray and place in the refrigerator.
Remove the chicken from the soup and shred. After the chicken has been shredded, run a knife through it once or twice to get it into smaller pieces. Return chicken to the soup and add 10g of salt. Taste the soup and adjust seasoning as needed with more salt and pepper.
To serve, pour soup in a bowl over the cooked noodles and top with a few cranks of black pepper.
Refrigerate any leftover noodles for up to 3 days. Any leftover soup will be good for 5-7 days in the refrigerator and up to 3 months in the freezer.