Steps to a keto-friendly roast beef:
Heat oven to 350° F.
Season the beef with 1 teaspoon salt and ½ teaspoon pepper and place in a large roasting pan.
In a bowl, combine the tomatoes, garlic, thyme, oil, ¼ teaspoon salt, and ¼ teaspoon pepper.
Scatter the tomato mixture around the meat and roast to the desired doneness, about 1 hour for medium-rare (internal temperature 125° F).
Transfer the beef to a cutting board and let rest at least 10 minutes before slicing. Divide among individual plates and serve with the tomatoes and garlic.