Preheat oven to 425°F.
Toss Brussels sprouts, cauliflower, and red onion with olive oil, salt, and pepper. Spread evenly on a sheet pan.
Roast vegetables for 20–25 minutes until browned and tender.
Heat olive oil in a large skillet over medium-high heat.
Season steak tips with salt, pepper, and smoked paprika.
Sear steak in batches for 2–3 minutes per side until browned and cooked to your preferred doneness. Transfer to a bowl.
In the same skillet, melt butter and add garlic, parsley, thyme, and salt. Cook 1 minute until fragrant.
Return steak tips to the skillet and toss in the garlic butter.
Serve steak tips over the roasted winter vegetables.