Watercress, new potato and avocado salad with a Spanish paprika and yoghurt dressing

We have an occasional supply of organic watercress from a pond on Hollyhill Farm in West Cork. When we get a consistent and abundant supply for a few weeks, I tend to experiment a little with It, but nothing works as well for me as a generous helping as a salad first course for dinner. Potatoes and watercress just love each other but the day we created this salad, the two things I was excited about were the watercress and a tin of Spanish paprika. (Well, what gets you excited?) The other In