Soaking the onion mellows its sharpness. If you can't find fresh horseradish, add 2 tablespoons prepared horseradish to the crème fraîche mixture.
Ingredients
1/4 small red onion, thinly sliced
2 tablespoons crème fraîche
2 tablespoons extra-virgin olive oil
1 tablespoon fresh lemon juice
1 tablespoon red wine vinegar
6 cups torn escarole hearts (from about 2 heads)
2 tablespoons rinsed capers
Kosher salt, freshly ground pepper
1/4 cup shaved peeled horseradish
Directions
Soak onion in a small bowl of ice water at least 30 minutes. Drain and pat dry.
Whisk crème fraîche, oil, lemon juice, and vinegar in a large bowl. Add escarole, capers, and drained onion; season with salt and pepper and toss to coat.
Top salad with horseradish and season with more pepper.
DO AHEAD: Onion can be soaked 2 hours ahead. Drain just before using.
