Combine the beef consomme, soy sauce, lemon juice, liquid smoke and garlic in a large roasting pan; if you need to use a disposable pan. Place the brisket in the marinade, fat-side up. Cover tightly with foil. Marinate in the refrigerator for 24 to 48 hours.
when you are ready; pre-heat oven to 300'F
keeping the foil on the pan cook the brisket until fork-tender, about 40 minutes per pound (6 to 7 hours). Transfer to a cutting board, slice against the grain and put the slices back into the cooking liquid. Serve immediately, spooning the juice over the slices
You can store the meat in the juice in the fridge for a couple of days, remove the fat once it solidifies.