Put the crushed peppercorns on a large plate and firmly press both sides of all the steaks on to them, ensuring all are well covered.
Place steaks on large plate, cover with cling film and chill in fridge for some 2 hours or so.
Cut 2.5cm pieces from the green ends of the spring onions and slice into strips. Place the strips in a bowl of water and chill until curled. Thinly slice the remaining onions.
Heat oil and 1/2 of the butter in a large frying pan until butter begins to foam. Add steaks and cook on both sides on a medium heat to desired state (about 1 to 2 minutes each side for rarish - 2 minutes plus for medium-rare). Remove steaks from pan, transfer to a warm plate and set aside.
Add non-curled spring onion to pan and cook for 1 minute. Pour in stock and brandy, increase heat to high, bring to boil and boil rapidly for 2 minutes until liquid slightly reduced. Turn off heat, whisk in remaining butter and season with salt if required.
Arrange steaks on serving plates, pour sauce over each one and garnish with the curled spring onion.