In the Netflix documentary *Salt Fat Acid Heat*, Samin Nosrat says this when she is making sofrito and she is about to put olive oil into the pan:

> 
> This is one of those important things that I think home cooks always
>  forget, is how important it is to pre-heat the pan. You have to heat
>  the pan before you heat the oil.
> 
> 
> 

Why do you need to heat the pan before putting the oil in?