Impersonal "you", "we" and "one"

Question

In Italian one can make a passive construction by adding the so-called "si passivante" to the third person singular or plural form of the verb. Albeit I'm not sure if the following definition makes sense to/for an English mother tongue, literally the "si passivante" is the "si" that makes the verb passive.

Italians, especially if they are high educated people, generally prefer impersonal constructions and the "si passivante" construction can be used to explain to someone how to do something without giving the impression of having a direct/personal relation with the hearer (spoken case) or with the reader (written case).

In English language I have observed that the impersonal construction is made using "one", "you" or "we".

So, let us consider the following example:

Italian version: "Prima si taglia la cipolla e si mette nel tegame, poi si aggiungono i pomodori tagliati a pezzetti e si lasciano cuocere per mezzora.

English version: First, 'you'/'we'/'one' cut(s) the onion, 'you'/'we'/'one' put(s) it in the pan, then 'you'/'we'/'one' add(s) the tomatoes cut into small pieces, and 'you'/'we'/'one' leave(s) them to cook for half an hour.

Assuming that 'you' is 1 case, 'we' is 2 case and 'one' is 3 case, which is between the three the most impersonal construction in cases like these? Cases in which, I repeat, there is no reason to refer to any singular person in particular.

Answer 1

One is certainly the most impersonal of these constructions; but it is so emphatically impersonal that it comes off as pompous and unnatural.

First one cuts (sliced? diced?) the onions and puts them in a pan; then one adds the tomatoes, diced small, and leaves this to cook for half an hour.

One step less formal is a passive construction:

First the onions are cut and put in a pan; then the tomatoes are added, diced small, and this is left to cook for half an hour.

Construction with you or we is chattier, but not particularly personal or familiar:

First we cut the onions and put them in a pan; then we add the tomatoes, diced small, and leave this to cook for half an hour.

But the most usual way to write this is with imperatives:

First cut the onions and put them in a pan; then add the tomatoes, diced small, and leave this to cook for half an hour.

This is neither personal nor peremptory—it's just the ordinary way of writing instructions.