Step 1

In a cast iron skillet or Dutch oven, heat butter. Add onions and sauté over medium heat, stirring frequently, until lightly caramelized, 7-10 minutes. Add mushrooms and garlic, and sauté until heated, 2-3 min. Transfer the onion mixture to the bottom of your slow cooker.

Step 2

Place the roast into the hot pan. Increase the heat to high and sear the meat on all sides, 1-2 minutes per side, to lock in the juices. Once the meat is seared, nestle the meat over the onion mixture in the slow cooker.

Step 3

Reduce the stove-top heat to medium and add the warm beef broth to the hot pan. Scrape the suck bits from the pan while the broth simmers. Add the Worcestershire and soy sauce to the broth, mixing to combine. Pour the warm broth mixture over the meat in the slow cooker.

Step 4

Cover the slow cooker and cook your roast on low heat for 3-5 hours. (The thickness of your roast will directly impact cooking time. If your roast is thin (under 2 inches), expect it to cook quickly (it may even cook in 2 hours). If it is thicker, it will take longer.

Step 5

In not using an in-roast probe thermometer, check the roast after 2 hours, and again every hour by inserting a thermometer into the center of the thickest part of the roast. (Better yet, if you have an in-oven probe thermometer or a sensor thermometer for your slow cooker, you can set it for 130F.) You are looking for an internal temperature of 130F for a medium rare roast (of 140F for a medium roast).

Step 6

Once the roast has reached the desired temperature, remove it from the slow cooker to your serving dish, along with the onions and mushrooms. Cover it with aluminum foil and let it rest for 10 minutes. (The temperature should continue to increase 5-10 degrees as it rests.)

Step 7

Transfer the remaining cooking juices into a saucepan. Turn the heat to medium-high and bring the mixture to a simmer. Slowly sift ¼ cup of flour into the warm juice, whisking constantly to thicken into a smooth sauce. Continue to simmer the mixture, whisking occasionally until it thickens into a gravy, 10-15 min.

Step 8

Serve the roast, sliced thin against the grain, and veggies topped with the gravy, as desired.

Step 9

Leftovers, make great sandwiches!