Cut potatoes into even-sized cubes and boil in salted water for 12 to 15 minutes until fork-tender. Starting these first ensures they finish at the same time as the other components.

Pat the steak dry and season generously with salt and black pepper on both sides. Heat olive oil in a large skillet over medium-high heat and sear the steak for 4 to 5 minutes per side for medium-rare. Let it rest for a few minutes after cooking.

In the same or a separate skillet, melt butter over medium heat and add minced garlic. Cook for 30 seconds, then add sliced bell peppers and sauté for 3 to 4 minutes. Add the shrimp, paprika, and Cajun seasoning, and cook for 3 to 4 minutes until shrimp turns pink.

Drain cooked potatoes and add butter, heavy cream, and sour cream while still hot. Mash to desired consistency, season with salt and black pepper, and fold in fresh parsley.

Arrange the steak on a plate, top with the shrimp and peppers, and serve with a generous portion of creamy mashed potatoes on the side. Garnish with extra parsley if desired.