200 gmbeef fillet or lean rump, trimmed of sinew, finely chopped3cornichons, finely chopped6cocktail onions, finely chopped3 tspsalted capers, rinsed, drained and finely chopped1 tbspfinely chopped chives¼cup (firmly packed) flat-leaf parsley, finely chopped1egg yolk1 tbspDijon mustard1dash each of Tabasco sauce, Worcestershire sauce and Cognac, or to taste3 tsptomato sauceHorseradish cream200 gmcrème fraîche50 gmfinely grated fresh horseradish2 tspchardonnay vinegar1 tspDijon mustardShoestring fries1extra-large desiree potato (about 200gm)For deep frying:vegetable oil
For horseradish cream, combine all ingredients in a bowl and season to taste with sea salt. Refrigerate until required.
For shoestring fries, cut potato into matchstick-size pieces and blanch in boiling water for 2 minutes, drain and place on layers of absorbent paper to dry. Preheat oil in a deep fryer or large deep saucepan to 180C and deep-fry shoestring potatoes in batches until golden (2-3 minutes), season to taste and keep warm.
Meanwhile, place meat in a bowl, add remaining ingredients and mix to combine. Season to taste.
Form beef mixture into patties on plates using an 8cm-diameter cutter. Make a well in the centre and spoon in some horseradish cream, then serve immediately with shoestring fries to the side.