Heat vegetable oil in a large pot over medium heat.
Add beef cubes and brown on all sides.
Remove beef and set aside; drain excess fat if necessary.
Add onions and garlic to the pot; sauté until translucent.
Stir in bell peppers and cook for another 5 minutes.
Add diced tomatoes and cook for 3 minutes.
Return the beef to the pot and mix well.
Pour in beef broth and add cumin, oregano, salt, and pepper.
Bring to a boil, then reduce heat to low and cover.
Simmer for 1.5 to 2 hours, until beef is tender, stirring occasionally.