Step 1Place the chicken, onion, carrots, potatoes (but not the noodles), celery and bay leaves in a large stew pan or soup pot. Pour in enough water to cover the ingredients by about 1 inch. Bring to a boil. With a large spoon, remove the foam from the soup's surface. Add salt, pepper and cumin to taste. Cover and cook over low heat, occasionally skimming off the foam and fat, until the chicken is tender, about 45 minutes.
Step 2Add the zucchini, mushrooms and garlic and bring to a simmer. Cover and cook over low heat until the vegetables are tender and the soup is well flavored, about 15 minutes. Discard the bay leaves.
Step 3If adding noodles, bring a saucepan of water to boil and add salt. Add the noodles, stir and cook uncovered over high heat until tender, about 5 to 7 minutes. Drain well. Keep the noodles in a separate dish so they won't soften when you reheat the soup.
Step 4Skim the fat from the broth with a large spoon. If you refrigerate the soup until cold, the fat solidifies on top and can be easily removed. Remove the chicken and discard its skin. Leave the pieces whole or cut off the meat, discarding the bones. Return the chicken to the soup or save part of it for other uses.
Step 5Reheat the soup to a simmer. Add the dill and more salt and pepper, if needed. Divide the noodles among shallow soup bowls, then ladle the hot soup over them.