Place the oil, onions, and ½ teaspoon salt in a large saute pan over medium heat. Cook, stirring occassionally, until the onions are golden brown, about 20 minutes. Remove from the heat and set aside to cool for 15 minutes.
Place the remaining ingredients and the remaining ½ teaspoon salt in a medium bowl, add the cooled onions, and stir to combine.
Refrigerate for at least 1 hour and stir again before serving.
Note: This dip is even better when made a day ahead.