Place the beef brisket in a baking dish. In a bowl, mix the onion soup mix, diced tomatoes and green chiles, tomato sauce, and garlic powder. Pour over the brisket.
Step 3
Loosely cover the brisket with foil. Bake 3 hours in the preheated oven, or to an internal temperature of at least 145 degrees F (63 degrees C).