Heat olive oil in a skillet over medium-high heat. Brown the London Broil in small batches. Place the meat in the bottom of a crock pot.
Deglaze the skillet with red wine vinegar. Reserve the drippings.
Layer vegetables over the beef.
Pour cream of mushroom over the top. Sprinkle with garlic, oregano, salt, and pepper.
Pour reserved drippings over the soup.
Cover and cook on low heat for 6 to 8 hours.
Serve over rice.