London Broil in the Crockpot takes only 11 ingredients & 15 minutes of active prep. This cozy, comforting slow cooker classic is a cold-weather favorite!
Heat the oil on medium-high in a large skillet. Add the London broil and sear for 2-3 minutes. Flip the London broil, and sear the other side for 2-3 minutes more. Remove and place in the slow cooker.
In a small bowl, mix together the beef broth, rosemary, Worchestershire sauce, thyme, garlic, onion powder, and salt until combined. Pour over the meat in the slow cooker.
Place the butter on top of the meat and close the lid. Slow cooker for 8 hours on low until the meat is tender and almost falling apart.
Transfer to a cutting board and allow to rest while you make the gravy. In a small bowl, whisk together the cornstarch with the cold water until well combined. Whisk the cornstarch into the boiling liquid remaining in the slow cooker until thickened (see notes).
Cut or shred the London broil, then serve over mashed potatoes. Top with gravy from the slow cooker!
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Notes
The gravy will thicken better if you leave the slow cooker on while you make it and the liquid is still boiling or VERY hot. If the gravy is a little too thin, mix another 1 tbsp cornstarch with 1 tbsp cold water and whisk into the gravy.