But my very very favourite watercress recipe is a chinese watercress soup: boil some water, put in some thinly sliced pork and simmer till cooked, put in watercress (just roughly torn), season. It's the best thing (and possibly the quickest thing) ever. I wish I have some now.
Thank you very much everyone, I had a mammoth watercress cooking, made a delicious soup (can't believe I haven't attempted watercress soup before), did a pesto too (was lovely as a quick lunch with pasta and for marrinating some chicken before baking).
I unfortualnately could not track down Marry Berry's aga receipe but it did inspire the baked chicken and watercress.
I am watercressed out! One bag did end with my neighbour...