Combine the onion and ground beef in a skillet over medium-high heat and cook, until ground beef is cooked through and crumbled. Drain any excess fat and return skillet to stove top.
Add in the tomato sauce and taco seasonings and stir over medium-low heat. Let the mixture simmer, until the sauce is thickened and flavors have had a chance to enhance, about 5 to 7 minutes.
For the Tacos:
Serve the taco meat while hot with the tortillas and other toppings of your choice. Enjoy!