In a medium saucepan, over medium heat, heat the olive oil.
Add the garlic and onions; cook until the onions have softened; stirring occasionally.
Add the remaining sauce ingredients; simmer very slowly, stirring occasionally, for about 30 - 40 minutes, or until the sauce reaches a brush able consistency,
Let the sauce cool for a half hour, or so, then puree the sauce in a food processor or with an immersion blender.
Save leftover sauce by bottling it, in mason jars, or freezing in small airtight containers.