Sauce Fanatic
Heat the oil in a medium-sized saucepan over medium-high heat. Add the onions, garlic, and serrano pepper; sauté for 2 or 3 minutes, stirring occasionally until the ingredients soften.
Reduce the heat to medium-low. Add the tomatoes and cook for 5 or 6 minutes, stirring occasionally.
Add the oregano, cumin, chili powder, and salt to taste; simmer for about 10 more minutes, until the liquid is reduced.
Use the sauce as-is if you like the texture or let it cool down and process it in a blender if you prefer a smoother sauce.
Enjoy!