In a large skillet or frying pan, heat the vegetable oil over medium heat.
Add the chopped onions and cook until they become translucent, about 2-3 minutes.
Add the minced garlic and diced red bell pepper, and cook for an additional 2-3 minutes until the pepper softens.
Add the minced beef and break it apart with a spatula. Cook until it's browned and fully cooked, about 5-7 minutes.
Season the beef mixture with ground cumin, paprika, chili powder, salt, and black pepper. Stir well to evenly distribute the spices.
Let the mixture simmer for another 2-3 minutes, allowing the flavors to meld. Taste and adjust the seasoning if necessary.