Lettuce, the most basic salad ingredient, varies very much in type; there is the normal round lettuce loosely packed with floppy leaves, which has a mild, pleasant flavour, and is ideal on its own with chopped fresh herbs and a good vinaigrette. There is Iceberg lettuce or crisp lettuce, very tightly packed with hardly any taste but a refreshing crunchiness, and there is my favourite, the Cos lettuce, with its long, dark green, crisp leaves, which has the best flavour of all. Very popular, too, are the tightly packed Little Gem lettuces which have both crispness and flavour, and can be stored in the refrigerator far longer than other salad leaves. There are also very decorative lettuces which make leaf salads so pretty. Watercress and cress both have a peppery bite which is nice combined with creamy flavoured, rich slices of avocado. Raw mushrooms are wonderful in salads, and absorb a flavourful vinaigrette made with extra virgin olive oil.