Preheat your grill to high heat.
Season the London broil steak with your favorite salt-free seasoning or marinade. Place the steak on the hot grill and cook for about 4-5 minutes per side, or until it reaches your desired level of doneness. For a rare steak, aim for an internal temperature of around 125°F (52°C).
Once cooked to your liking, remove the steak from the grill and let it rest for a few minutes. Then, chop the steak into bite-sized pieces.
In a 1.5-quart crock pot, combine the chopped barbecued London broil steak, diced onion, minced garlic, carrots, celery, small golden potatoes, diced tomatoes (with their juices), low-sodium beef broth, bay leaf, dried thyme, paprika, freshly ground black pepper, and the finely chopped serrano pepper. Stir well to combine all the ingredients.
Cover the crock pot and cook on low heat for 6-8 hours or on high heat for 3-4 hours, until the potatoes are tender and the flavors have melded together.
Remove the bay leaf from the stew. Taste and adjust the seasoning if needed.
Ladle the beef stew into bowls and garnish with chopped fresh parsley if desired. Serve hot and enjoy the comforting flavors!