1.Chop the onions, garlic and cilantro.
2.Heat a medium saucepan over medium heat, add olive oil.
3.Add onions and garlic sauté over medium heat, until soft and transparent.
4. When the onions are tender add cilantro and oregano and sauté for less than a minute.
5.Add tomato sauce, dilute the tomato sauce with water and add sugar to neutralize the acidity of the tomato.
6.Simmer the mixture over low heat uncovered for 15-20 minutes so that all the flavors marry together.
7.Serve the sauce with Chiles Rellenos or with fried or baked meat or fish.