Iced Avacado Soup

2 ripe avocados, halved and stoned
2 teaspoons lemon juice
1 celery stalk, very finely chopped
1 tablespoon tomato purée
450 nil/3/4 pint plain low-fat yogurt
1-2 drops of Tabasco
salt
freshly ground black pepper
300 ml/I/2 pint vegetable stock
snipped chives, to garnish

Do not prepare this soup more than an hour before you intend to serve it.

Spoon the avocado flesh into a bowl, add the lemon juice and beat to a smooth paste. Beat in the celery, tomato purée, yogurt, Tabasco, and salt and pepper. Add sufficient vegetable stock to obtain a thick but liquid soup, then adjust the seasoning. Chill in the refrigerator, resting the bowl on a bed of ice to hasten the chilling process. Serve garnished with chives.

SERVES 4