1. Preheat oven to 400°F (200°C).
2. Peel onions and garlic and slice in the food processor. Transfer to a 9- x 13-inch (20- x 30-cm) baking pan. Add seasonings and olive oil and mix together very well. Bake uncovered for an hour and a half until deeply brown, stirring every 20 minutes to ensure even baking. Add optional additional parsley 10 minutes before the end of baking, for more herb overtones. Cool and refrigerate.
3. I recommend taking out of the fridge about an hour before serving and/or warming a little on top of a pot or slow cooker.
This doubles easily and freezes well. Keep in mind the proportions of 2 onions to 1 garlic. For a great serving idea, spread a piece of challah with avocado. Top with diced sun-dried tomatoes and onion-garlic dip. It’s amazing!
In the recipe above, most of the oil is absorbed by the onions and garlic and it becomes more like a topping. If you prefer a more liquidy texture, keep all ingredients as is, but double the olive oil from 6 tablespoons to 12, or 3/4 cup.