A great potato salad is a must at every barbecue. The key is to use really fresh potatoes from a good greengrocer. Chat potatoes work well because they are creamy and small, but if you want to use a larger potato, the royal blue variety also has a lovely creamy texture. Purslane, a succulent used in Greek and Italian cooking, adds a delicious tang here.
Note Tuscan red onion is a long oval-shaped red onion. If it's unavailable, substitute half a Spanish onion. Purslane is available from select greengrocers. If it's unavailable, use extra watercress.