Preparation Place steak on a flat plate or small rimmed baking sheet and freeze uncovered overnight. Once frozen, wrap tightly in plastic, transfer to a resealable plastic bag, and keep frozen for up to 3 months. (Freezing it uncovered before wrapping ensurs that no condensation forms on the steak, which could cause dangerous splattering during cooking.) Preheat oven to 275°F. Pour vegetable oil into a large skillet to a depth of 1/8". Heat over medium-high until shimmering. Carefully place frozen steak in skillet and cook until deeply browned on underside. Turn and continue to cook until second side is deeply browned, 5–6 minutes more. Transfer to a wire rack set in a rimmed baking sheet. Season both sides with 1 tsp. salt and 1/2 tsp. pepper. Transfer pan to oven and bake steak until an instant-read thermometer inserted into the center registers 120°F for medium-rare, 40–45 minutes. Let rest 10 minutes before slicing. While steak rests, wipe out skillet and cook tomatoes, garlic, and olive oil (adding tomatoes while pan is cold prevents splattering) over medium-high heat. Once sizzling, add rosemary and vinegar and season with remaining 1/2 tsp. salt and 1/4 tsp. pepper. Continue to cook, stirring occasionally and pressing tomatoes with the back of a spoon, until tomatoes have burst and a thick sauce has formed, 4–5 minutes. Remove from heat and stir in butter. Serve steak with sauce spooned over.
Preparation Place steak on a flat plate or small rimmed baking sheet and freeze uncovered overnight. Once frozen, wrap tightly in plastic, transfer to a resealable plastic bag, and keep frozen for up to 3 months. (Freezing it uncovered before wrapping ensurs that no condensation forms on the steak, which could cause dangerous splattering during cooking.) Preheat oven to 275°F. Pour vegetable oil into a large skillet to a depth of 1/8". Heat over medium-high until shimmering. Carefully place frozen steak in skillet and cook until deeply browned on underside. Turn and continue to cook until second side is deeply browned, 5–6 minutes more. Transfer to a wire rack set in a rimmed baking sheet. Season both sides with 1 tsp. salt and 1/2 tsp. pepper. Transfer pan to oven and bake steak until an instant-read thermometer inserted into the center registers 120°F for medium-rare, 40–45 minutes. Let rest 10 minutes before slicing. While steak rests, wipe out skillet and cook tomatoes, garlic, and olive oil (adding tomatoes while pan is cold prevents splattering) over medium-high heat. Once sizzling, add rosemary and vinegar and season with remaining 1/2 tsp. salt and 1/4 tsp. pepper. Continue to cook, stirring occasionally and pressing tomatoes with the back of a spoon, until tomatoes have burst and a thick sauce has formed, 4–5 minutes. Remove from heat and stir in butter. Serve steak with sauce spooned over.