Heat all ingredients (except ice) in a saucepan until salt is dissolved. Cool slightly then add enough ice cubes to chill brine.
Put raw turkey in a large enough container to hold it and the brine. Fill with brine (top up with more water if needed to cover turkey). Refrigerate 8-24hrs. Drain, pat turkey dry, and allow to rest at room temperature for one hour prior to roasting.
Notes
If not filling turkey with stuffing, put 2 fresh lemon halves inside the cavity.