Lime juice is one of the most important juices in a bar.
If it's not possible to use fresh squeezed lime juice, only the best-quality bottled juice should be used. Note that lime juice is sold both unsweetened and sweetened (Rose's - see related ingredients) on bottles.
To get the most juice from a lime bring it to room temperature, then roll it on the counter with the flat of your hand while pressing down on the fruit to soften them up before squeezing.
A medium sized lime has about 1 oz. of juice.