In a large nonstick skillet, heat the oil (2 tablespoons). When oil shimmers, add onions (2 cups) and sugar (1/2 teaspoon). Sauté over medium heat, stirring occasionally, until the onions are caramelized, about 10 minutes.
Stir in soy sauce (2 teaspoons), black pepper (1/4 teaspoon), garlic powder (1/4 teaspoon), and onion powder (1/4 teaspoon). Cool completely.
In a medium bowl, stir together sour cream (3/4 cups), mayonnaise (3/4 cups), chives (2 tablespoons), and cooled caramelized onion.