Add the oil and butter to a large Dutch oven or soup pot and place it over MEDIUM-HIGH heat. When the butter has melted, add the carrots, onion, and celery and cook, stirring occasionally, for 6 to 8 minutes or until the vegetables are fork tender. Add the parsley, garlic, caraway seeds, salt, and pepper and cook for a minute or two until fragrant. Add the broth, corned beef, cabbage, potatoes, and bay leaves.