Wash turnips well and slice them thinly (a mandolin works well if you have one). Place turnip slices in a small bowl and toss with the salt. Let rest until there is a pool of liquid on the bottom of the bowl, about 30 minutes. Drain turnips of the salty water and pack into a pint sized mason jar. Add vinegar, sugar, pepper and ginger slices. Apply a watertight lid and shake to combine. Place pickled turnips in the fridge and chill before eating. Pickles can be eaten within an hour of being made and will keep for at least a week.