16 asparagus spears, stems peeled and trimmed
1 shallot, finely chopped
陆 tsp whole black peppercorns
salt and freshly ground black pepper
2 tbsp white wine vinegar
50ml/2fl oz white wine vinegar
125g/4陆oz unsalted butter
4 duck eggs
2 large egg yolks
8 slices air-cured ham, ideally British (alternatively, use serrano or Parma ham)