How to Make It
In a large, shallow glass or ceramic dish, combine the grapes, garlic cloves, parsley, bay leaves, rosemary, olive oil, salt and chile. Add the flatiron roast, turning to coat with the marinade. Cover with plastic wrap and refrigerate overnight, turning a few times.
Preheat the oven to 325°. Remove the beef from the marinade and pat dry with paper towels. Strain the marinade through a food mill and reserve. Set a medium flameproof roasting pan over moderately high heat. Add 2 tablespoons of olive oil and heat until shimmering. Add the beef and cook over moderately high heat, turning once, until browned, about 10 minutes; transfer to a plate.
Add the remaining 2 tablespoons of olive oil to the roasting pan along with the onion, garlic, carrots, celery and orange-zest strips. Cook over low heat, stirring occasionally, until the vegetables are softened, about 10 minutes. Add the red wine, bring to a boil and cook over moderately high heat until reduced by one-third, about 5 minutes. Add the stock and bring to a boil. Stir in the reserved marinade. Add the beef and cover with foil. Transfer the roasting pan to the oven and braise the meat for about 2 1/2 hours, turning once halfway through, until very tender.
Transfer the beef to a carving board and thickly slice across the grain. Arrange the beef on a platter. Skim any fat from the braising liquid; spoon the liquid over the meat with some of the vegetables and serve.
The beef flatiron is usually precut and sold as individual steaks. This whole flatiron roast will need to be ordered from the butcher in advance.