First cover the beetroot in some olive oil and season. Wrap in foil and raost in an oven at 180 degrees for 45 mins depending on the size of the beet.
It is cooked when you can push a knife in with little resistance.
Bring your steak up to room temp before cooking - this stops it going tough.
Rub in a little oil and seasoning into both sides and heat a little oil in an oven proof frying pan.
Cook the steak on one side on a high heat for 3-4 mins depending on the thickness.
Turn the steak and put the pan in the oven - remove the beetroot.
While the steak is cooking for another 8- 10 mins in the oven remove the beetroot from the foil to cool a little.
Dress your watercress with a little olive oil and lemon juice.
Slice the beet and add to the watercress. Remove the steak from the oven and rest for a few mins under foil.
Slice and place on the watercress.
Add a dollop or two of horseraddish sauce and serve.