This is just a more "detached" way of giving instructions rather than just using the imperative, which is more direct and requires the writer to use either a polite or familiar tone, where the infinitive is neutral in that respect.

Thanks Sergi!

Hi bobby, Actually when someone say "Freir el ajo picado" they are saying "Freíd el ajo picado" (Imperative) But this is a very very common mistake that most natives do. Technicaly it's wrong but we all say it that way. So in most cases you will hear the imperative using -er, -ir, -ar. (Infinitive form) E.g. of imperative sentences: (Vosotros) coger una fruta = Coged una fruta (Pick up a fruit) (Vosotros) saltar hasta que os canséis = Saltad hasta que os canséis. (Jump untill you are exhausted) A common Spanish conversation that always comes up is this one: - Freir el ajo picado + Querrás decir "Freíd" (Meaning that you said it wrong) - Oh cállate! We are all waiting that the RAE accept that as a correct form for imperative :P