Rinse the corned beef under cold water to remove excess salt. Set it aside while you prepare the vegetables.
Peel the onion and carrots, then chop them into small chunks. Next, wash and slice the celery into thin half moons.
In a large Dutch oven or saucepan, heat the olive oil and butter over medium heat. Once the butter has melted, add the chopped carrot, onion, and celery, cooking them for about 10 minutes until they’re soft.
While the vegetables are cooking, cut the corned beef into cubes.
Once the vegetables are ready, add the cubed corned beef to the pan. Pour in the chicken broth, water, bay leaf, and black pepper. Stir everything together and bring it to a boil.
After it reaches a boil, reduce the heat to low, cover the pan with a lid, and let it simmer for 90 minutes. This slow cooking will develop the flavors.
As you're nearing the end of the cooking time, peel and cube the potatoes.
Add the cubed potatoes and shredded cabbage to the pot after the 90 minutes is up. Let these cook for an additional 45 minutes.
Finally, check the seasoning of the soup and add more black pepper if needed.
For those who prefer a slow cooker method, you can complete steps 1 through 4, then transfer everything into the slow cooker. Cook on low for 8 to 10 hours.
