Peel onions and quarter lengthwise; slice thinly. Heat a large non-stick skillet over medium heat. Add onions and sprinkle with salt. Stir occasionally until onions are hot, 8-10 minutes. Meanwhile, stir together olive oil, ANGOSTURA® aromatic bitters and vinegar. Pour over onions and stir. Continue to cook on medium heat, stirring occasionally, until onions turn golden brown, 30-40 minutes. Remove from heat and cool completely.

Stir caramelized onions into sour cream. Refrigerate 3-4 hours or overnight for flavors to develop. Serve with chips of your choice.