Heat 1 teaspoon of the oil in a large skillet over medium-high heat. Season the steak with ½ teaspoon salt and ¼ teaspoon pepper.
Cook the steak to the desired doneness, 5 to 6 minutes per side for medium-rare. Let rest for 5 minutes before slicing.
Meanwhile, in a large bowl, whisk together the vinegar, mustard, remaining tablespoon of oil, ¼ teaspoon salt, and ⅛ teaspoon pepper.
Cut away the peel and pith of the orange. Working over the vinaigrette bowl, cut out the orange segments, adding them to the bowl as you go.
Add the arugula, hearts of palm, and shallot and toss to combine. Serve with the steak and sprinkle with the pomegranate seeds (if using).