Ingredients
3 to 3 1/2 pounds thick-sliced beef arm roast (cut into 1- to 1 1/2-inch thick slices)
1 (1-ounce) packet dry onion soup mix
2 (10.5-ounce) cans condensed cream of mushroom soup
1 cup beef broth (or water, if you prefer a milder gravy)
Directions
Pat the thick-sliced arm roast dry with paper towels. If there are any very large pieces of fat hanging off the edges, trim them lightly, but leave some fat for flavor and tenderness.
In a medium bowl, whisk together the dry onion soup mix, condensed cream of mushroom soup, and beef broth until mostly smooth. It doesn’t have to be perfect, just well combined so the flavors blend as they cook.
Spread a thin layer (about 1/2 cup) of the gravy mixture over the bottom of a 5- to 7-quart slow cooker to keep the beef from sticking.
Lay a single layer of beef slices over the gravy in the slow cooker. Spoon some of the gravy mixture over the top of the beef, making sure each piece is coated. Continue layering beef and gravy until all the meat is in the slow cooker and is generously covered in the sauce. Pour any remaining gravy over the top.
Cover the slow cooker with the lid and cook on LOW for 7 to 9 hours, or until the beef is very tender and easily pulls apart with a fork. Avoid lifting the lid during the first several hours so the heat stays steady and the meat can slowly break down.
Once the beef is fork-tender, gently stir or nudge the slices to coat them in the gravy. Taste the gravy and adjust the seasoning if needed with a pinch of salt or pepper, keeping in mind that the onion soup mix is already salty.
For a slightly thicker gravy, remove the lid during the last 20 to 30 minutes of cooking and let some of the steam escape while the slow cooker is still on LOW, stirring once or twice so nothing sticks.
Serve the smothered beef hot, spooning plenty of the rich brown gravy over each portion. It should pull apart easily with a fork, with steam rising as you lift the slices from the slow cooker.