Cut the beef and vegetables into bite-sized pieces.
Heat olive oil in a pan and stir-fry the beef.
Add onion, garlic, bell pepper, and tomato in order, and stir-fry.
Add tomato sauce and mix well.
Season with salt, pepper, and paprika powder.
Cover with a lid and simmer over medium-low heat for 20 minutes.
Taste and adjust seasoning if needed.