Heat the vinegar, water, sugar, and salt in a medium saucepan over medium heat. Stir until the sugar and salt dissolve, about 1-2 minutes, depending on what type of sugar you use.
1 cup white vinegar, 1 cup water, 2½ tablespoons brown sugar, 1 heaped teaspoon salt
Add all the radishes to a colander and rinse under fresh water.
2 cups red radishes
Remove stalks and tails from the radishes then thinly slice the radishes into rounds or half moons (the thinner the better).
Add flavoring (we added whole black peppercorns and fennel seeds, but up to you!)
1 teaspoon whole black peppercorns, ½ teaspoon fennel seeds
Pour the brine over the radishes, then stir in the peppercorns and fennel seeds. Let the jar cool to the touch then label it with the date pickled and chill in the refrigerator.
Pickled radish slices will be ready to eat in a few hours, although their flavor and color will intensify if left overnight.