Transfer the beef to a warm platter, cover loosely with foil, and leave to rest for 15–20 minutes. To make the gravy, pour off any excess fat from the roasting pan, leaving behind a couple of tablespoons, then place the pan over medium heat. Add the shallots, garlic, and a little salt and pepper. Cook for about 4–6 minutes, stirring frequently, until the shallots begin to soften. Add the flour and stir for a few more minutes.