I'm all for using seasonal British foods. Apart from the issue of food miles, eating foods grown on our doorstep is much better for us, as they're more in tune with nature and are tastier and fresher.
Watercress is in season from April to September and although it's usually relegated to a measly garnish on the plate, I look upon it as a delicious and health-giving vegetable in its own right. I use the hot peppery leaves to add a kick to salads; their pungent flavour also makes flavoursome soups, sauces and flavoured butters and goes particularly well with eggs.
The hot peppery taste comes from the mustard oil in the plant and its strong flavour stimulates the taste buds and digestion. Young leaves contain less mustard oil and so have a milder flavour.
Curiously the peppery taste of watercress has a cooling effect, a paradox that was noted by the celebrated 14th century French chef Taillevent, who was also the first person to include it on a menu. He prepared a lavish banquet and served watercress after the fourth course, writing on the menu 'Watercress, served alone to refresh the mouth'.
Watercress was so popular in the past that every spring it was sold tied it into bunches in Covent Garden by London street sellers. Buyers ate the bunches from their hands, rather as we would eat an ice cream cone!
Hippocrates the 'father of medicine' opened what was probably the world's first hospital near to wild watercress growing in a stream, so that he could use the watercress to treat his patients. In fact watercress is one of the most nutritious vegetables and is a rich source of vitamins and essential minerals. That's why the French call their watercress soup potage de santé or 'healthy soup'.
It's not a good idea to eat watercress found growing in the wild though, as it's likely to be polluted and may carry liver fluke. Cultivated watercress is grown on washed gravel and nourished with pure fresh spring water.
My favourite way of enjoying watercress is in a sandwich made with good quality bread generously spread with butter and packed with plenty of crisp, fresh watercress. In Germany watercress is eaten with meats, sausages and smoked fish. I like to serve watercress with sea trout or salmon, where its refreshing flavour is the perfect complement to the rich tasting fish.