Shredded greens salad

Zest and juice 2 of the limes into a big salad bowl. Top and tail the remaining 2 limes to sit flat on a chopping board. Use a small serrated fruit knife to cut away the peel and pith in downward strokes. Cut the segments from the pith and roughly chop. Add to the salad bowl with the apples, fennel, cucumber, celery, spring onions and olive oil. Cover and chill until ready to serve.