You can substitute unsalted chicken stock for the homemade. If you do, simmer with the water, stock, peppercorns, sugar, star anise, and ginger, and proceed with recipe from there.
Preheat oven to 425°.
To prepare stock, place first 4 ingredients on a jelly-roll pan. Drizzle with canola oil; toss. Roast at 425° for 40 minutes or until deep golden brown, turning once.
Transfer roast turkey parts and vegetables to a large stockpot. Discard fat from jelly-roll pan. Pour 1 cup water into jelly-roll pan; carefully scrape up browned bits, and add to pot. Stir in remaining 5 cups water, chicken stock, peppercorns, sugar, star anise, and ginger. Bring to a boil. Reduce heat to low; simmer stock mixture 1 hour. Strain through a fine sieve into a large bowl. Discard solids.
Wipe out pot; return strained stock to pot. Stir in fish sauce, salt, and leftover turkey; cook over medium heat 5 minutes or until thoroughly heated.
Prepare noodles according to package directions, omitting salt and fat; drain and divide evenly among 6 bowls. Ladle about 1 1/3 cups stock over each serving; drizzle each serving with 1/2 teaspoon chili oil. Top evenly with bean sprouts and remaining ingredients.