Clean and slice the radishes. I prefer thinly sliced.
Add salt and pepper to taste. You can use more than you think because some of the salt and pepper comes off in the vinegar.
Add enough vinegar to coat the slices and to have just a little extra at the bottom of the bowl.
Notes
Substitutions:You can use any clear type of vinegar. If I don't have apple cider vinegar, I use either plain vinegar or red wine vinegar. You do not want to use a sweet balsamic type vinegar.
Nutrition (I am not a nutritionist. These are estimates only)