Add olive oil to a large skillet set over medium heat. Add diced onion and garlic and season with salt and black pepper, to taste. Stir to combine and sauté, stirring occasionally, until the onion softens and develops some color, approximately 4-5 minutes.

Add beef to skillet and cook, stirring occasionally, until browned, approximately 4-5 minutes.

Add taco seasoning and fire-roasted tomatoes and green chilis and stir to combine. Cook, stirring frequently until tomatoes are heated through and the beef mixture is thoroughly coated in the taco seasoning, approximately 2-3 minutes. Taste, and add additional taco seasoning, if desired.

Remove from heat and top with shredded cheese. Cover for 1-2 minutes or until cheese is completely melted. Serve immediately with desired accompaniments. Enjoy!