- Slow Cooker London Broil – Classic and Authentic Post 5 brings you an old-school favorite! Slow Cooker London Broil – Classic and Authentic uses simple, wholesome ingredients to create fork-tender beef infused with deep, savory flavor straight from a traditional kitchen. Ingredients: - 2–3 lb London Broil (top round steak) - 1 tbsp olive oil - 1 onion (sliced) - 3 cloves garlic (smashed) - 1 cup beef broth - 2 tbsp tomato paste - 1 tbsp red wine vinegar - 2 tsp dried oregano - 1 tsp dried thym