Heat olive oil in a large saute pan and cook the onions over medium-high until translucent, about 4 minutes.
Add the garlic and cook for an additional minute.
If you want the sauce super smooth, pour the onions, tomatoes, and seasonings into a blender. Blend until smooth, then pour the mixture into the saucepan and simmer for 20 minutes.
OR, if you like it chunkier, add the remaining ingredients to the onions and simmer for 20 to 25 minutes.