Season the tots with the paprika and half the Montreal seasoning. Bake according to the package instructions.
Meanwhile, melt the butter in a large cast-iron skillet over medium-high heat. Sprinkle the steaks on both sides with the lemon pepper seasoning and the remaining 2 teaspoons Montreal seasoning. Add the steaks to the skillet and cook for about 3 minutes per side for medium-rare. Remove to a cutting board to rest.
For the peppercorn horseradish sauce: Add the sour cream, mayonnaise, horseradish, peppercorns, Worcestershire and Montreal seasoning to a bowl, then stir until well combined.
Mound the tots on a platter and place the steaks alongside. Pour the sauce into a bowl to serve. Garnish with fresh parsley.