Heat the olive oil in a large pot or Dutch oven over medium heat.
Add the diced onion and sauté for about 5 minutes, until it becomes translucent.
Stir in the minced garlic and cook for another minute, until fragrant.
Add the sliced carrots and diced potatoes to the pot, and continue cooking for 5-7 minutes, stirring occasionally.
Pour in the beef broth and add the shredded corned beef. Mix well.
Stir in the chopped cabbage, thyme, black pepper, and bay leaf.
Bring the soup to a boil, then reduce the heat to low. Cover and let it simmer for about 30 minutes, or until the vegetables are tender.
Taste the soup and add salt as needed.
Remove the bay leaf before serving.
Garnish with fresh parsley if desired.