Press the 4 sirloin steaks into a plate of crushed black peppercorns. Transfer the steaks to a plate and leave to infuse with the pepper for 3-4 hrs or overnight in the fridge. Bring the steaks up to room temperature before frying. Heat a splash of oil in a frying pan and sear the steaks for 1 min on each side to seal. Reduce the heat, add a knob of butter and cook for another 4 mins, turning once. Transfer to a plate and allow to rest. To serve, cut each steak into thin slices and thread onto small wooden skewers. Serve with small bowls of good-quality, ready-made Bearnaise sauce as a dip.