1. Trim and discard ends from endive and slice heads crosswise on the diagonal.
2. In a large bowl, mix lemon juice, olive oil, horseradish to taste, mustard, and pepper.
3. Add endive, salmon, and capers to bowl and mix to coat. Press eggs through the large holes of a grater, or chop.
4. Spoon salad onto plates; top with eggs. Add salt to taste.