01 - Heat a splash of oil in a large soup pot or Dutch oven over medium heat. Add the diced onion, sliced carrots, and sliced celery. Sauté for 5 minutes until vegetables are softened and fragrant.
02 - Stir in the minced garlic and tomato paste. Cook for 1 minute, stirring constantly, until the garlic becomes fragrant and the tomato paste is well incorporated.
03 - Add the diced potatoes, chopped cabbage, bay leaves, dried thyme, and black pepper to the pot. Stir well to combine all ingredients.
04 - Pour in the beef broth and water. Increase heat to bring the mixture to a boil, then reduce heat to maintain a gentle simmer. Cook uncovered for 20 minutes, or until the potatoes are just tender when pierced with a fork.
05 - Stir in the diced or shredded cooked corned beef. Continue simmering for an additional 10 to 15 minutes, allowing the beef to heat through and the flavors to meld together.
06 - Taste the broth and adjust seasoning with salt as needed. Remove and discard the bay leaves before serving.
07 - Ladle the hot soup into individual bowls and garnish with chopped fresh parsley if desired.