Prepare the Radishes and Beets: Trim the radish tops and tails and wash them thoroughly. You can use a sink with a mild soap solution if needed, but rinse them well to ensure no soap residue remains. Scrub the beets clean and slice them into thin half-moon shapes.
Slice the Serrano Chilies (Optional): Cut the chilies into thin circles if you like an extra kick of heat.
Layer the Ingredients: In each clean mason jar (32-ounce size), begin layering: Start with a few slices of beet at the bottom of the jar. Add radishes, filling the jar halfway. Sprinkle 1 teaspoon of sliced Serrano chilies on top of the radishes. Add 1 bay leaf. Add more beet slices to create another layer. Fill the rest of the jar with whole radishes, packing them tightly.
Add Seasoning and Liquid: To each jar, add: 2 tablespoons of kosher salt, 1 teaspoon of peppercorns, ½ cup of white distilled vinegar. Top off the jars with filtered water, leaving about ½ inch of space at the top.
Seal and Ferment: Screw the lids onto the jars tightly. Place the jars on your counter at room temperature for 2 days to allow the radishes to ferment slightly.
Refrigerate and Enjoy: After 2 days, transfer the jars to the refrigerator to stop the fermentation process and enhance the crispness of the radishes. They are ready to be enjoyed.