How to Make It
Season steak with ¾ teaspoon of the salt and ½ teaspoon of the pepper. Heat 1 tablespoon of the oil in a large skillet over medium-high. Add steak and cook until deeply brown on both sides, 3 to 5 minutes per side for medium-rare. Transfer to a cutting board and let rest for 5 minutes.
Meanwhile, place beets and 2 tablespoons water in a microwave-safe bowl. Cover tightly with plastic wrap and microwave on high until beets are tender when pierced with a knife, about 5 minutes.
Whisk together vinegar, honey, mustard, remaining 2 tablespoons oil, and remaining ¼ teaspoon each salt and pepper in a large bowl. Add beets and lettuces and toss to combine. Slice steak against the grain and serve on top of salad along with cheese and pistachios.