Speedy sauteed cauliflower, Parmesan, and greens flatter tender skillet-cooked beef.
Heat a large skillet over medium-high. Season steaks with salt and pepper. Place in skillet, and cook until medium-rare, 5 to 6 minutes per side (reduce heat if browning too quickly). Transfer to a cutting board (reserve skillet), and tent with aluminum foil to keep warm.
Add cauliflower, garlic, and 1/2 cup water to skillet; season with salt and pepper. Cook, tossing occasionally, until cauliflower is browned and crisp-tender, 8 to 10 minutes. (If bottom of skillet becomes too dry, add 1/4 cup more water.)
Meanwhile, in a large bowl, whisk together lemon juice and oil; season with salt and pepper. Add arugula, hot cauliflower, and Parmesan to dressing in bowl; toss (arugula will wilt). Serve steaks and vegetables together; garnish with lemon wedges.