Ingredients
3 1/2 to 4 pounds beef brisket, flat cut, trimmed of excess hard fat
2 (10.5-ounce) cans condensed French onion soup
1 (1-ounce) packet dry onion soup mix
Directions
Preheat your oven to 300°F (150°C). Choose a roasting pan or deep 9×13-inch baking dish that will fit the brisket snugly and has room for foil to cover without touching the meat too much.
Place the brisket in the baking dish, fat side up if there is a fat cap left. This helps keep the meat moist as it cooks.
In a medium bowl, whisk together the condensed French onion soup and the dry onion soup mix until well combined. It will be thick and very flavorful—no extra salt needed.
Pour the onion mixture evenly over the brisket, making sure the top is completely coated and the liquid pools around the sides. Use a spoon to scoop some of the onion bits onto any bare spots.
Cover the baking dish tightly with heavy-duty aluminum foil, sealing all the edges well so the steam stays inside. This is what makes the brisket fall-apart tender.
Place the covered brisket in the preheated oven and bake for 3 to 3 1/2 hours, or until the brisket is very tender when pierced with a fork. For a larger or thicker brisket, you may need up to 4 hours. Avoid opening the foil too often so you don’t lose moisture.
Once the brisket is fork-tender, carefully remove the pan from the oven and let it rest, still covered, for 15 to 20 minutes. This rest helps the juices settle back into the meat and makes slicing easier.
Transfer the brisket to a cutting board, reserving all the onion gravy in the pan. Slice the brisket across the grain into thin slices. If it’s extremely tender, you can simply pull it into chunks with two forks.
Return the sliced or pulled brisket to the baking dish, nestling it back into the onion gravy so every piece is coated. Spoon extra gravy over the top before serving.
Serve the brisket hot, straight from the baking dish, with plenty of the rich brown onion gravy spooned over each portion.
Variations & Tips
For a smaller family, use a 2 to 2 1/2 pound brisket and reduce the French onion soup to 1 can and the dry onion soup mix to about 2/3 of the packet; keep the oven temperature the same but start checking for tenderness around 2 1/2 hours. If you like a thicker gravy, remove the brisket at the end, set the pan on the stovetop, and simmer the onion juices on medium heat until slightly reduced, or whisk in 1 tablespoon of cornstarch mixed with 2 tablespoons cold water and cook until it thickens. For extra richness, you can add a small splash of Worcestershire sauce or a pat of butter to the pan juices after baking, but it’s not necessary. Picky eaters who don’t love visible onions often still enjoy this because the onions cook down very soft; you can blend the sauce with an immersion blender for a smoother gravy if that helps. This same method works well with other tougher cuts like chuck roast if you can’t find brisket—just keep the 3-ingredient rule and adjust cooking time until it’s fork-tender. Leftovers reheat beautifully; store the meat in its gravy so it doesn’t dry out, and warm gently in a covered dish in the oven or microwave with an extra spoonful of water or broth if needed.