To make the beef roast, preheat the oven to 375 degrees F.
Season the beef with salt and pepper. Season the tomatoes with salt, pepper, and herbs de Provence.
Place a medium, heavy roasting pan or Dutch oven over high heat. Heat the olive oil. Sear the beef over high heat on all sides. Turn off heat. Place the seasoned tomatoes around the seared beef and place the pan in the oven. Roast until a meat thermometer reads 130 degrees F. for medium rare, 135 for medium, about 30 to 40 minutes. Take the roast out of the oven, tent loosely with foil, and let rest for 10 to 15 minutes. The internal temperature of the meat should rise 5 degrees F more and the juices will redistribute into the roast.
To make the sauce, place the parsley and garlic in a food processor and pulse until the parsley is finely chopped. Add the red pepper flakes, salt, red wine vinegar and the roasted tomatoes from the beef pan and process until pureed. Add the olive oil in a steady stream with the machine running.
To serve, slice the roast and place on a serving platter. Drizzle a little sauce over the meat. Serve the remaining sauce in a small bowl alongside.