Heat a large pot over medium heat and add the ground beef. Cook until browned, breaking it up with a spoon as it cooks.
Add the chopped onion and minced garlic to the pot. Stir and cook for 3 minutes until the onion softens.
Stir in the diced potatoes, diced tomatoes, beef broth, salt, pepper, and oregano. Bring the mixture to a boil.
Reduce the heat to low, cover the pot, and simmer for 20 minutes until the potatoes are tender.
Add the drained green beans and stir gently. Simmer uncovered for 5 more minutes to heat through.