1) Chop off the tops from the fennel and slice the roots off. Slice bulb in half lengthwise. Pop out the center core section which can be a bit fibrous. Then slice the sections as thin as possible.
2) Add the fennel slices to a bowl with juice of a lime and orange.
3) For the orange, peel them and then cut the 1/4 inch slices. Cut those slices in half to make them easier to eat.
4) Toss everything together with the cilantro and serve immediately or let marinate for a few hours.
Serve with any seafood.