In a large pot or Dutch oven, heat the vegetable oil over medium heat.
Add the beef chunks and cook until browned on all sides. Remove the meat and set aside.
In the same pot, add the chopped onion and minced garlic. Sauté until the onion is soft and translucent, about 5 minutes.
Stir in the chopped tomatoes, bell pepper, and tomato paste. Cook for another 2-3 minutes until the tomatoes start to break down.
Stir in the ground cumin, paprika, dried oregano, black pepper, and cayenne pepper (if using). Cook for 1-2 minutes to toast the spices.
Return the browned beef chunks to the pot and mix well with the spices and vegetables.
Pour in the beef broth and bring to a boil.
Reduce the heat to low, cover the pot, and let it simmer for about 1.5 to 2 hours, or until the meat is tender and can be easily shredded.
Once the meat is tender, remove it from the pot and shred it with two forks. Return the shredded meat to the pot.
Add the diced potatoes, sliced carrots, and green beans to the pot. Continue to simmer for an additional 20-30 minutes, or until the vegetables are tender.
Season with salt to taste.
Garnish with chopped fresh cilantro before serving.
Enjoy your meal!