Christmas ham with potato salad

Name: Christmas ham - Christmas recipes
Yield: 8-12
Ingredients: 2 onions, peeled and quartered; 1 teaspoon black peppercorns; 2 bay leaves; 3.5kg unsmoked ham on the bone (pre-soaked, if necessary); 1 litre apple juice; 750g waxy salad potatoes (such as charlotte); Salt and freshly ground black pepper; 2 tablespoons cold-pressed rapeseed oil; 1 tablespoon white-wine vinegar; 4 tablespoons mayonnaise, preferably home-made; 4 tablespoons fromage frais or natural yogurt; 2 sticks celery, very finely chopped; 6 spring onions, about 75g, trimmed and finely chopped; 30g cornichons, finely chopped; 2 tablespoons finely chopped flat-leaf parsley; 1 large egg, beaten; 4 tablespoons Dijon mustard; 4 tablespoons grainy mustard; 2 tablespoons demerara sugar; 90g fresh white breadcrumbs; Chicory leaves