Trim stems and roots from radishes. Slice into 1/4 inch rounds.
Place in 2-quart non-reactive saucepan along with vinegar and water. Bring mixture to boil. Reduce heat and simmer over medium heat until radishes are somewhat tender, about 8 to 10 minutes.
Transfer radishes to bowl with a slotted spoon. Reserve cooking liquid.
Let cool separately to preserve crispness of radishes. When both have cooled, combine in airtight container and refrigerate overnight.
Serve the next day for best crispness. Makes 3 cups.
