This recipe isn't traditional cold brew. Traditional cold brew is soaked overnight using a cheesecloth and beans method where the coffee grounds soak in the water. However, this recipe is similar to traditional cold brew in the fact that the espresso when mixed with the grapefruit juice creates a foam layer effect. You can use traditional cold brew in this recipe and it will work just as well as using espresso shots. Refrain from using iced coffee if you can as it's too watered down for this recipe and will take away from the strong flavor of this drink.