In a large bowl, mix together all of the ingredients for the steak tartare until the mix starts to bind together
Shape the mix into 4 patties using a round cutter (there will be sauce leftover in the bowl, do not discard as it is needed for step 4)
Toast the slices of sourdough
Plate up the steak tartare patties and drizzle with a little of the sauce left in the bowl. Top with a raw egg yolk and accompany with a slice of sourdough bread and rocket. Season and serve immediately
