Next sauté the garlic and onion together with the olive oil in a large skillet (at least 10″) until tender and golden. Keep the heat low enough to allow the onion to soften without getting browned.
Simmer the sauce over low heat until the flavors are combined, about 8-10 minutes. Try not to stir the sauce much. The thinnest liquid rises to the top and creates a layer that helps to prevent splattering.