Heat oil in a medium saucepan over medium-high heat. Add the chopped onion and cook until just browned, about 5 minutes or so. Stir in the garlic, chili powder, cumin, and oregano and cook for about 30 seconds, stirring constantly. Sauteing your spices for a few seconds will give your sauce a fuller flavor.
Add in the tomato sauce and chicken broth. Bring mixture to a simmer and cook for approximately 8 to 10 minutes, stirring occasionally.
Remove from heat & use in your favorite Mexican-inspired recipes! Keep refrigerated for up to one week.
Once the sauce is done simmering, you can choose to pour the sauce through a fine mesh strainer to remove the onions, but I choose to keep the onions in the sauce