Prepare the taco seasoning by combining all ingredients in a bowl. Stir to combine and transfer to an airtight container. Set aside.
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 for 4-5 minutes, stirring occasionally, until the onion softens and develops some color.
Add beef to skillet and cook for 4-5 minutes, stirring occasionally, until browned. Remove from heat and carefully drain excess fat from skillet.
Add taco seasoning and canned fire-roasted tomatoes and green chilis to the pan and stir to combine. Cook for 2-3 minutes, stirring frequently, until tomatoes are heated through and the beef mixture is thoroughly coated in the taco seasoning. 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!
Notes
*You can use more or less Cayenne pepper as desired, from a pinch (⅛ tsp) to half a teaspoon.
Remaining taco seasoning can be stored in an airtight container with a tight-fitting lid for several months.