Load up
Chapter 3 / Scene: The Puppet Queen and play a little further. You will come to this area where you will have to fight a lot of enemies. A grenade will be here to pick up every time. If you fail to get 3 enemies you can reload the checkpoint and try again. You will start directly before the grenade.
Go into the top building with the blown out windows and look right. A few enemies will shoot you from this position and will for the most part stand in the same position.
Cook your grenade and throw it at the to get this trophy.