Watercress & Leek Soup

1 lb Leeks, trimmed, washed &

-- sliced 2 pk Watercress, washed

1/2 oz Margarine

3 1/2 c Stock

1 ts Cornstarch

Salt & pepper Fry leeks & watercress in margarine in a large pot over a low heat for 15 minutes. Keep a lid on the pot, but stir occasionally, don't let it brown. Add stock, bring to a boil & simmer for 10 minutes. Dissolve cornstarch in a little cold water & add to the soup. Blend till smooth, reheat & serve.