Pastrami and roast beef are similar but not the same thing.
Roast Beef is the beef that is roasted and is why it's called roast beef.
The Pastrami is made from the brisket and although it's beef it's not the same cut of beef that is used for roast beef as it is for pastrami.
Pastrami uses a different cut of beef than roast beef does.
The pastrami also goes through a smoke process to cook the pastrami and is not roasted like roast beef.
Both the pastrami and roast beef are already cooked if you buy the beef already roasted.
Pastrami does not need cooked before being eaten or served and can be served or eaten cold.
You don't have to or need to cook pastrami before eating it.
The pastrami is already cooked because the pastrami you buy in stores goes through a smoking process that smokes the pastrami and cooks it while it smokes it.
So you can eat the pastrami cold or heat it up.
It doesn't take long to prepare the pastrami because it doesn't require much time to heat it up.
There's no need to cook it like you would other meat because the pastrami is fully cooked and ready to eat.
You just need to heat the pastrami up before you eat it or serve it if you want too.
The pastrami does not require being heated up first but the pastrami in my opinion is more enjoyable after being heated up.
But you can use cold pastrami to make sandwiches or just eat the pastrami cold if you prefer it.