Add the oil to a large nonstick sauté pan set over medium heat. Once the oil is hot, add the onions, sugar, and a pinch of salt and cook, stirring, until the onions are caramelized, about 10 minutes.
Set the caramelized onions aside to cool.
In a medium bowl, stir together the sour cream, soy sauce, garlic powder, 1/2 teaspoon pepper and the cooled caramelized onions.
Cover the dip with plastic wrap and refrigerate it until ready to serve.