Fennel is similar to onion. You need to start by removing the top leafy, green section and the bottom roots. Next, remove the outer layer from the bulb to reveal the white flesh of the bulb underneath. Once the outer layer is removed, slice the fennel bulb in half lengthwise. Take each half and slice them both in half lengthwise again. Turn the fennel bulb onto its outside layer. Towards the bottom, you should see a hard white area. Cut the hard part away and then thinly slice the quarter of the fennel ball lengthwise.