In a large skillet or saucepan, heat the olive oil over medium heat. Add the diced onion and cook for about 3 minutes, until it starts to soften. Stir in the minced garlic and cook for an additional 30 seconds.
Increase the heat to bring the mixture to a boil. Once boiling, cover the pan, reduce the heat to the lowest setting, and let it cook for 12 minutes. Remove the pan from heat and let it sit, covered, for 5 minutes.