Except for the potatoes, all the other ingredients should be chopped about the same size, so that they mix well.
Boil the eggs and, as soon as they are cooked, cool them down in some ice water; once cool, peel them and then chop them.
Peel and chop the onion in dice and, OPTIONAL, bathe for 10 minutes in a bowl of ice water, then drain and allow to dry well spread out on a clean tea towel.
Peel and chop the carrots; OPTIONAL: you can lightly boil the carrots for 3-4 minutes, so as to eliminate most of its raw flavor, if unliked, while still maintaining some crunch.
Wash and peel the celery, then chop it to size.
Place potatoes and chopped vegetables in a large mixing bowl; choose a bowl that allows you to easily mix the salad, not one that just fits it.