Heat the olive oil in a large pot over medium heat. Add the ground beef and cook until browned, breaking it up with a spoon as it cooks.
Add the onion, carrots, and celery to the pot. Stir and cook for 5 minutes until the vegetables begin to soften.
Stir in the zucchini and garlic. Cook for another 2 minutes.
Pour in the beef broth and diced tomatoes. Add the oregano, salt, and black pepper. Bring the mixture to a boil.
Add the elbow noodles and reduce the heat to a simmer. Cook for 8 to 10 minutes, stirring occasionally, until the noodles are tender.
Remove the pot from the heat and let the stew rest for 2 minutes. Ladle into bowls and top with chopped parsley.