Preheat your oven to 425°F for the Brussels sprouts.
Rinse and trim the Brussels sprouts, then cut them in half. Toss with olive oil, salt, and black pepper until evenly coated.
Spread the Brussels sprouts on a baking sheet and roast in the oven for 18-20 minutes, or until tender and slightly crispy on the edges.
Meanwhile, pat the steak dry with a paper towel. In a small bowl, combine the chopped fresh rosemary, thyme, minced garlic, and a pinch of salt and black pepper.
Coat the steak evenly with the herb mixture, pressing gently to adhere.
Heat a cast iron skillet over medium-high heat. Once hot, add the steak and sear for about 3-4 minutes per side for medium-rare, adjusting time based on your preferred doneness.
Allow the steak to rest for 5 minutes after cooking.
Plate the steak alongside the roasted Brussels sprouts and serve immediately.