Heat a medium sized pot on medium heat. Wash and cut tomatoes in half.
Smash the garlic cloves and add them to the heated pan along with the whole black peppers and sauté for a minute or two, until the garlic is fragrant.
Add the tomatoes, salt, onion powder, and Mexican oregano to the pot. Mix everything together and bring to a boil on medium high heat. Adjust the heat back to a low, cover and let cook on low for about 45 minutes. Stir occasionally to make sure nothing sticks to the bottom.
Once the sauce reaches the desired thickness, turn the stove off. Let the sauce cool for 5-10 minutes and then add the fresh basil, if using.
Let cool completely. Use a blender to process the sauce if a smoother texture is desired.
Divide and store in the refrigerator for 3-5 days or freeze in freezer friendly jars for longer.