In a large pot or Dutch oven, heat the olive oil over medium heat.
Add the chopped onion and minced garlic, sautéing until the onion is translucent (about 3-4 minutes).
Add the ground beef to the pot and cook until browned, breaking it up with a spatula (about 5-7 minutes). Drain any excess fat if necessary.
Stir in the diced carrots, celery, and bell pepper. Cook for about 5 minutes until the vegetables begin to soften.
Add the can of diced tomatoes (with juices), beef broth, green beans, corn, thyme, oregano, salt, and pepper. Stir well to combine.
Bring the mixture to a boil, then reduce the heat to low. Cover the pot and let it simmer for about 20 minutes, stirring occasionally.
Taste and adjust seasoning if necessary. Serve hot.