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, garlic, and carrots to the pot. Stir and cook for 5 minutes until the onion softens.
Stir in the zucchinis, diced tomatoes, beef broth, potatoes, oregano, salt, and black pepper.
Bring the mixture to a boil, then reduce the heat to low. Cover and simmer for 25 minutes until the potatoes are tender.
Remove the pot from the heat and let the stew rest for 5 minutes before serving.