This is a brave dish to get into because it sounds so basic. Think of all the food writing which promises the world and then, when you follow it, delivers very little. This is the contrary example. It sounds too obvious, but delivers much more.
The recipe specifies borlotti beans, but you could use a different variety and still have a good result. Fresh beans are best and rehydrated dried beans are fine, but even tinned are acceptable, if drained and rinsed well.