1 Place London Broil in crock pot. 2  Slice onions and peppers into rings and place on top of London Broil. 3  Top all with stewed tomatoes. 4  Pour wine over tomatoes (if using). 5  Cook on low 8-10 hours. Place London Broil in crock pot. 2  Slice onions and peppers into rings and place on top of London Broil. 3  Top all with stewed tomatoes. 4  Pour wine over tomatoes (if using). 5  Cook on low 8-10 hours.