There are a number of recipes for this about and it is really worth making.  It takes 10 mins to prepare and is fantastic with a plate of risotto.

1 fennel
1 orange
12 black olives
glug olive oil
sprinkle of salt

Cut off base and tops of fennel and slice thinly from the bottom up.  Cut the top and bottom off the orange, then carefully cut off all the peel and pith.  Cut thin slices from the bottom up, then break them up a bit.  Slice across the olives into thirds.  Toss together all of the ingredients in a bowl and serve.