Put the spring onions, celery and fennel in a large salad bowl. Pour in the dressing and toss well. Place half the cucumber and half the mixed leaves, Romaine lettuce and rocket in the bowl.

Apart from traditional lettuces, such as 'Cos', 'Iceberg' and 'Butterhead', there are many others to try, including loose-leaf types and oak leaf lettuce, radicchio, rocket and endive.