How to Make It
In a saucepan, cover the beets with water and bring to a boil. Add a generous pinch of salt and simmer over moderate heat until tender, about 20 minutes. Drain well and let cool, then cut into bite-size pieces.
In a bowl, cover the onion with ice water. Add a generous pinch of salt and let stand until crisp, 20 minutes. Drain well; pat dry.
In a bowl, toss the beets and onion with the olive oil and vinegar. Season with salt and pepper and toss again. Serve.