For best results, place your steak out on the counter for 30 minutes to an hour before cooking, this will allow the steak to come closer to room temp and cook more evenly.
Peel and chop your potatoes into large chunks. Place in a medium pot and cover with water about 2 inches above the potatoes. Add salt to the pot and bring to a boil. Boil under the potatoes are fork tender about 12-15 minutes.
Slice your cabbage thinly with a mandolin. Once the potatoes are cooked, remove them from the boiling water with a slotted spoon. Keep the pot on and boil your cabbage until tender for about 3-4 minutes. Remove and set aside.
Flatten out your steak with a meat mallet for even cooking. In a small bowl combine the salt, pepper, smoked paprika, garlic powder and dried parsley. Combine the spices and rub evenly over both sides of the steak. Set aside and heat a cast iron griddle or pan to medium-high heat.
Place the olive oil in the pan and cook the steak for about 3-4 minutes per side until reaching an internal temp of 130-135°F. Once the steak has cooked, remove and allow to rest on a cutting board for 3-5 minutes.
While the steak is cooking, roughly chop your cabbage and mash your potatoes with a potato masher in a medium bowl. Add the milk, cream, parsley, butter, salt and pepper and continue to smash and mix until you have a smooth consistency. If your potatoes have cooled off at this point, you can return them to the medium pot and heat over low to medium heat to fully melt the butter and potatoes.
Slice your steak and serve with the potatoes. Add extra melted butter and parsley on top, enjoy!