Prep: 1. Quarter mushrooms and slice scallions. 2. Remove stems from arugula. 3. Season steak with salt and pepper. Make: 1. Heat 1 tablespoon of oil over medium-high heat. 2. Cook steak to desired doneness, 3-5 min. per side for medium-rare. Let rest at least 5 min. before slicing. 3. Wipe out the skillet and heat remaining tablespoon of oil over medium-high heat. 4. Add mushrooms, salt and pepper. Cook, tossing occasionally, until tender and browned, 5-6 min. 5. Stir in vinegar. Remove from heat and stir in cream. 6. Divide the arugula, steak, and mushrooms among plates and sprinkle with scallions.