40 g butter, 1 onion, salt, 1 tbsp flour, 400 ml milk, 420 g watercress, 75 ml double cream
Heat the butter in a pan and add the onion. Season and cook gently until soft, not coloured. Stir in the flour and cook for a minute. Gradually stir in the milk and 250 ml water. Bring almost to the boil, cover, and simmer for 5 min. Prepare a large bowl of iced water. Bring a large pan of water to the boil and plunge in the watercress to wilt. Drain and plunge the watercress into the iced water. Squeeze the cooled watercress and add to the pan. Puree thoroughly, add the cream and season to taste. Reheat if necessary: delicious hot or chilled.
plunge – thrust
wilt – go limp
squeeze – compress
*image from BBC Good Food