Season the steak and char grill for around 2 minutes on each side, and then allow to rest in bowl in a warm area. Strain the juices from the resting bowl and add the Worcestershire sauce and seasoning to the juices.
To make the relish slice the onion and finely dice the chilli. Place in a bowl and add the vinegar. Leave to marinate for at least 3 minutes, but the longer the better.
To make the crisps peel and thinly slice the parsnip, potato and beetroot on a mandolin. Deep fry at around 160ºC until golden and crisp, then season and drain.
To assemble, spread the softie with wholegrain mustard. Top with rocket and red chard leaves and some of the relish. Slice the beef into slices then place on the leaves. Drizzle with the juices and serve.