Pat the roast dry with a paper towel and season with salt and black pepper. Heat vegetable oil in a large skillet over medium-high heat. Sear the beef for 3 to 5 minutes per side until browned. This extra step creates the best results by building flavor before slow cooking London broil.

Place London broil into your 6-quart slow cooker.

Add the sliced onions, carrots, and garlic around the roast.

In a small bowl, whisk together the cup of beef broth, ketchup, red wine vinegar, Worcestershire sauce, cornstarch, Italian seasoning, cayenne, salt, and pepper.

Pour the sauce over the top of the meat and add the bay leaf.

Cover and cook on low for 6 to 8 hours, or until the roast is fork tender.

Slice against the grain or shred the beef, then spoon the flavorful broth over the top before serving.