Aim to use at least 2 types of leaves, one sweet, like a Cos, and one frilly and bitter, such as frisée, or a different colour, such as red radicchio. Optional extras include watercress or rocket, and lots of fresh chopped parsley, chives and other tender herbs. Crunchy vegetables like spring onion, cucumber, and green peppers are best left for mixed salads. A well-flavoured