1. Slice the radishes into rounds.
2. In a non-reactive saucepan, bring the water, vinegar, salt, and sugar or honey to a boil, until the sugar and salt are dissolved. Remove from heat and add the peppercorns, garlic and chile pepper, if using.
3. Pack the radishes in a clean pint-sized jar, and pour the hot liquid over them, adding the garlic and chile into the jar as well.
4. Cover and let cool to room temperature, then refrigerate.