Heat the vegetable oil in a large skillet or wok over medium-high heat.
Add the beef strips and cook until browned on all sides, about 4-5 minutes. Remove the beef from the skillet and set aside.
In the same skillet, add the sliced onion, green bell pepper, and minced garlic. Cook until the vegetables are slightly softened, about 3-4 minutes.
Stir in the sliced tomatoes and cook for an additional 2 minutes.
Return the cooked beef to the skillet.
Add the soy sauce, red wine vinegar, aji amarillo paste, ground cumin, paprika, salt, and black pepper. Stir well to combine and cook for another 2-3 minutes, allowing the flavors to meld.
Stir in the chopped fresh cilantro.
Enjoy your meal!