In a large pot, add the beef and cover with water. Bring to a boil.
Reduce heat and skim off any foam that forms on the surface.
Add the quartered onion, garlic, and a pinch of salt.
Simmer for about 1.5 hours until the beef is tender.
Remove the beef, let it cool, and then shred it into bite-sized pieces.
Return the broth to the boil and add the carrots and potatoes.
Cook for about 10 minutes until the potatoes are tender.
Add the corn and zucchini, cooking for an additional 5 minutes.
Stir in the shredded beef and adjust seasoning with salt and pepper.
Serve hot, garnished with fresh cilantro and lime wedges.