Peel and chop the potato into cubes, boil them until soft but not mushy. Let them cool down completely (even better if are leftovers, straight from the fridge!).
Prepare the green beans by removing the top and bottom and cut in half. Put them into boiling water for 1 minute or 2 (I like mine very crunchy!), drain and let cool down completely (again, if you have cold leftover in the fridge is even better.
In a bowl add all the ingredients, seasoning and mix.
Notes
I love to prepare this salad and leave it in the fridge for a few ours or overnight, it amazing from cold and when the flavours had time to marinade together.