Twenty years ago, when I first returned to my native California from New York City, I tapped out a letter to the Food editor ...

Remove any old or damaged leaves and wash well before cooking. Romaine, Little Gem, iceberg, round lettuce, or bags of mixed leaves all work well. You can also use watercress, spinach and pak choi.

There are different varieties of radicchio from the large round lettuce-shaped radicchio chioggia to the slender stalky treviso. Most common in the UK is red chicory, an endive-shaped small radicchio.