Take an orange in the palm of your hand and with a small, very sharp knife cut out the segments from between the membranes, discarding the pips and any pith still attached. Repeat with the remaining oranges.
Place the orange segments and sliced olives in a bowl, then add the fennel and anchovies. Season with salt and pepper. Mix in the olive oil and vinegar, leave to marinate for 1 or 2 minutes and then serve. Decorate with the green feathery leaves from the fennel.
