Heat a large skillet on medium and add the onions and oil and cook until the onions cook and caramelize. Once the onions begin to caramelize, add the garlic to the pan.
As soon as the onions are caramelized, remove from heat and allow to cool.
Mix all the ingredients together and chill.
Dip can be made and stored in an airtight container for up to three days.
Notes
Turn the heat down to medium-low to low, all while frequently stirring them. The trick to caramelized onions is to cook them low and slow so the natural sugars in the onions will release and caramelize. This can take up to 15 minutes sometimes.
Make sure you scrape the sides and bottom of the pan to keep the onions from burning. They will turn a deep golden brown. If any part of them turns black, they're burnt and you should remove those pieces.