Place the meat in a large bowl, add the shallots, parsley, gherkins and capers. Beat in the egg yolks and season with salt and pepper; do not overwork the mix.
Leave in the refrigerator for 1 hour before use.
Divide the mix, using wet hands, into 4 x 200g evenly sized burgers.
Heat a chargrill or pan grill until very hot. Brush the burgers l