Heat the oil in a deep frying pan, add onion and garlic; fry them until the onion is clear. (There are people who skip this step and cook the noodles in boiled water, like spaghetti, but I prefer to fry the pasta before).
Add the fideo noodles and move constantly until golden.
Incorporate the water or chicken broth, zucchini, baby carrots, and cooked chicken breast.
Season with salt and cumin to taste.
A few minutes later, add the cilantro branches and chopped tomatoes.
Lower the stove heat to medium and let the soup cook only until the noodles and vegetables are soft.