When so many things are ripening all at once in the garden, this potato salad makes good use of several vegetables. My mother used to make this salad all the time in the summer when we had so many tomatoes and green beans in the garden. I have added pancetta and capers to her dish because I like the saltiness of the pancetta and capers with the potatoes.
When boiling the green beans and potatoes, make sure the the water is well salted and boiling before you add the vegetables. This kind of water will help the potatoes to hold their shape and keep the beans bright green. It is a method you should remember, because it makes a big difference. I have used separate pots to boil the green beans and potatoes in, but more often than not I use one big pot and boil the green beans first, scoop them out with a strainer and then add the potatoes to the same water. Why dirty two pots when you can do it with one?
If you are making this dish ahead of time and not serving it right away, you should plunge your cooked green beans immediately into an ice bath. This will retain their bright green color and stop them from further cooking. An ice bath is simply a large bowl full of ice water. Let them sit in the ice bath until they are cooled and then drain them and dry them thoroughly.
How long you cook the green beans is a matter of personal taste but I do not like the raw taste of an undercooked green bean. Too many people think that the right way to cook green beans is to leave them undercooked, which is wrong. I wrote about what Julia Child's opinion was on this subject in an earlier post. You don't want the green beans to be overcooked and mushy, but you want any raw flavor cooked out.
For the capers, don't use capers packed in vinegar. Buy capers packed in salt. Give them a little rinse before you use them. They have a superior flavor and are worth purchasing. I always have my pantry stocked with them.