Place water in a pot to boil, (or place chicken broth to boil).
Place dutch oven or large saucepan over medium heat with some oil of choice.
Cook onion for a couple of minutes and add fideo. Brown the fideo until slightly golden and fragrant, stirring frequently to ensure it doesn't burn.
Add bouillon and sazon to water and mix thoroughly.
Pour tomato sauce and seasoned water or broth into dutch oven or saucepan with fideo. Mix well and salt to taste, if needed.
Cover dutch oven or saucepan with lid and let simmer over medium heat until pasta cooked through, about 15 minutes.
Add more water or broth if soupier fideo is wanted.