With the rack in the middle position, preheat the oven to 170 °C (325 °F).
Cut a large 50-cm (20-inch) square of extra strength aluminum foil. If necessary, double the foil.
In a skillet, brown the roast on all sides in the oil. Season with salt and pepper. Remove the roast from the pan and set aside.
In the same skillet, brown the onions. Add oil as needed. Add the garlic, red wine and reduce for 3 minutes over high heat. Add the tomatoes and oregano. Reduce until the liquid thickens. Remove from the heat and add the olives. Season with salt and pepper.
Place half the vegetables in the centre of the foil. Top with the roast and pour the remaining sauce over the roast. Tightly close the foil to form a papillote. Place in a saucepan and cover.
Bake for approximately 2 hours and 45 minutes. Remove from the oven. Slice or break the meat with a fork and serve with potatoes and vegetables.
Recipes with the "Healthy Pick" stamp have been evaluated by a registered dietitian member of the Ordre professionnel des diététistes du Québec.