To prep the steak, allow it to come to room temperature for at least 30 minutes. Salt and pepper the steak before letting it sit to allow the flavor to penetrate the meat.
While the steak is coming to room temperature, toss potatoes in a medium bowl and drizzle with olive oil. Season the potatoes with salt and pepper and roast in a 425° oven for 25-30 minutes, until browned on the outside and tender on the inside. The potatoes can also be cooked in the air fryer if you have one. The air fryer will take 15-20 minutes at 385°.
While the potatoes cook, prep and set aside salad greens, tomatoes, and red onion.
Once the steak has rested for 30 minutes, heat a grill pan or barbeque to medium-high heat. Once hot, lightly oil the grill and cook the steak, searing well on both sides, for 10-15 minutes. For a more well-done steak, cook longer, but for a medium or medium-rare steak, cook for less time. Cook your steak to an internal temperature of 135°-145° for medium-rare to medium. Well done will be closer to 165° but I don't recommend cooking steak above 155° so it stays juicy and doesn't dry out.
After the steak is cooked to your liking, let it rest for at least 10 minutes before slicing. By this time the potatoes should be finished roasting.
While the steak rests, combine salad greens, tomatoes, onion, roasted potatoes, and enough dressing to moisten the salad. Toss to coat and transfer to a serving plate.
Top dressed salad with sliced steak, avocado, chives, and blue cheese. Drizzle on more dressing if needed and serve immediately.