Gently fry onion and garlic in a small amount of butter until transparent. Season lightly with salt and pepper, and add water and potato and boil until soft.

Pick over watercress and chop 4 or five sprigs and set them aside. Put onion and potato mixture in blender and puree. Add most of watercress, blend, re-season to taste and return to heat.

Bring mixture to boil and simmer for 2 or three minutes. Stir gently to prevent soup from sticking to bottom. Remove from heat.

This is the decision point. Either set aside to cool, then chill, or carry on to serve the soup hot.

Stir in cream and chopped watercress. Heap a teaspoon of caviar on each of the water biscuits and float one on each bowl of soup immediately prior to serving.

* Watercress soup, hot or cold - This thick, creamy soup is equally good whether served hot or cold. I have had watercress soup in restaurants, and my mother sometimes makes it, too, but this recipe is my own interpretation of the idea. Yield: Serves 4.

* Use the minimum amount of butter, oil, or margarine that will turn the onion transparent. Those who are particularly diet-conscious could dispense with this step, and with the cream. Don't overdo the garlic, 1/2 a small clove is ample since it is a background flavour, not one that you should be aware of.

* A caution regarding seasoning. Potatoes absorb a lot of salt so you may find it under-salted. The caviar on the other hand, is very salty. This, for me, is a delightful and important contrast. Guests can always add extra salt if they choose.

* Water biscuits are made by Carr's, amongst others, and can be found in most supermarkets, possibly in the gourmet food section.

They are variously known as water biscuits, water crackers and table water crackers. To my mind the best for eating with cheese are the high-bake ones, but the regular type are better for this recipe. If you can't find them, then any round dry bland low-salt cracker will do.

* A 2 oz jar of lumpfish caviar costs a little under $3.00, but it does keep in the fridge so you can get two batches of four servings from one jar. I suppose if budget is a prime consideration one could dispense with the caviar, too, but that would be like serving a martini without the olives. (Treasonable.)