How to fillet a lemon or orange
A very sharp knife is crucial, the fruit that has been sitting around and has become slightly wilted will be more difficult to fillet.
Slice the top and bottom off the orange or lemon. Run the knife along the sides from top to bottom, slicing off strips of the peel including the pith. Then cut out segments, running the knife in on the diagonal very close to the membrane - the segments should just drop from the fruit. Don't discard the remaining membrane - it's full of juice!