THE BEST:
Super Rad Rare-Dish Radish Relish!
Fermented Radish Delicacy!
Shred radishes (with a cheese grader, salad master, food processor, etc), then add salt and cover! Make sure to add enough salt but not too much (just like you would with sauerkraut) and make sure the radish pieces are covered in their own juice (there will be plenty of juice that comes from them to cover fully). You can leave a loose cloth lid or air-tight lid for faster fermentation.
I made a gallon and it was gone within a week!