In a medium saucepan, add the potatoes and broth. Bring to a boil and cook for 5-10 minutes until potatoes are fork tender.
Meanwhile, add the oil to a french oven or large skillet with sides. Add the diced onions and bell pepper, and saute for 10 minutes over medium/medium-high heat.
Add the cooked potatoes and the broth to the onions and bell pepper. Stir in the corned beef, bay leaf, garlic powder, and black pepper.
Simmer over medium/medium-high heat for 20 minutes
In a small bowl, stir together cornstarch and cold water (until no lumps remain). Reduce the heat to medium-low, and add cornstarch mixture to the dish. Stir well.
Remove the bay leaf and discard. Stir in the cabbage, and let cook for about 5 minutes until the cabbage is slightly wilted. Enjoy!