Remove the florets from the broccoli and discard. Trim one of the long sides of the stem so it is flat and, using a mandolin, slice lengthways into 1mm (1/32inch) thick slices. You will need 18 slices. Bring a small saucepan of water to the boil. Blanch the broccoli stem for 1 minute. Drain well and season with the oil, salt and pepper. Set aside and keep warm.