Caramelized Maui Onion Dip

Cooking time: 30 minutes plus cooling time. Prepare this delicious sauce at least an hour before cooking, so that the flavor opens up, and serve with potato chips in such quantities that they are enough for everything to the last bite.
Heat the oil in a large nonstick skillet over medium-high heat. Add the onion and cook, stirring occasionally, until browned, sticky and caramelized, about 20 minutes. If the pan starts to burn, reduce the heat to medium-low and add 1 tablespoon of water, stirring well. Transfer the onion to a small bowl and refrigerate until it cools, about 1 hour.Leave 1 tablespoon of onion. In a food processor, combine the remaining onion, sour cream, buttermilk, and salt until smooth. Transfer to a serving platter, sprinkle with the remaining onion, and refrigerate for at least 1 hour.Prepare in advance: for 2 days and refrigerate.Note: The nutritional analysis is based on 2 tablespoons of water.