Heat oven to 425° F. Toss the carrots, cauliflower, 3 tablespoons of the oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper on a rimmed baking sheet. Roast, tossing once, until browned and tender, 25 to 30 minutes. Let cool for 5 minutes, then coarsely chop.
Meanwhile, combine the pistachios, sesame seeds, and coriander on a separate rimmed baking sheet. Roast until lightly browned, 5 to 8 minutes.
Heat the remaining tablespoon of oil in a large skillet over medium-high heat. Season the steak with 1/2 teaspoon salt and 1/4 teaspoon pepper. Cook until an instant-read thermometer inserted into the thickest steak registers 130° F, 3 to 4 minutes per side for medium-rare. Let rest for 5 minutes before slicing against the grain.
Serve the vegetables tossed with the pistachio mixture over a dollop of hummus, with the steak and lemon wedges on the side.