Combine the red onion and vinegar in a bowl and sprinkle with walt and white pepper. Allow to sit at room temperature for 15 minutes, then drain.
Slice the oranges thinly crosswise, and use the tip of a knife to remove any seeds. Arrange on a serving dish and top with the red onion. Drizzle with olive oil and season to taste with more salt and white pepper. Serve garnished with fresh basil.