Cooking bags are specially manufactured heat resistant bags usually used to cook large cuts of meat like beef, turkey or pork. They allow the heat to circulate around the meat cooking it evenly while retaining moisture. The use of cooking bags can also shorten cooking time if used correctly. Cooking bags can be purchased from most grocery stores and there are a variety of brands available. You can season your cut of beef however you would normally season it when cooking without the bag, or follow this recipe. Assuming you follow the recipe, the beef should be ready in one and a half to two hours.
Preheat the oven to 160 degrees Fahrenheit. Coat the inside of the cooking back with the flour. Pour the flour into the bag. Pinch the open end of the bag firmly shut with your fingers and shake the bag so that the insides of the bag are fully coated with flour.
Place the bag into the baking dish and set it aside.
Prepare the beef. Trim any excess fat from the beef and set it aside.
Add all of your seasonings to the bag. In this case, add your salt, pepper, tomato sauce, water and instant bouillon to the bag. Shake the bag again to mix the contents. Prepare the vegetables and add them to the bag.
Gently place the beef inside the cooking bag. Close the bag with the nylon tie provided with the bag. Gently squeeze and roll the bag so that the contents fully coat the beef.
Place the bag in the dish. Use a sharp knife to make 5 or 6 small slits one-half inch wide at the top of the bag. Bake the beef for 1 1/2 to 2 1/2 hours, depending on how you well you like your beef cooked. Cook for 1 1/2 hours if you like it medium and 2 1/2 hours if you like it well done.
Remove the beef from the oven and let it rest for about 30 minutes. Carefully open the bag and place the beef into the dish. Pour the juice over the roast beef and carve.