In a small saucepan, over medium heat, sauté the onions and garlic in the olive oil until softened but not browned.
Add the remaining ingredients and simmer very slowly for up to an hour until the sauce thickens; stir often.
The sauce will thicken as it cools so reduce it to a consistency a little more watery than ketchup.
Remove from the heat and place in a mason jar; use lid; place in the refrigerator.
The sauce can be kept in the refrigerator for 2 weeks or so.
Make it last all summer by properly bottling it according to the prescribed method recommended by the mason jar manufacturer.
