Begin by washing and drying your fresh vegetables thoroughly to remove any dirt. Cut them into uniform, bite-sized pieces, ensuring even pickling.

In a medium saucepan, combine white vinegar, water, kosher salt, sugar, minced garlic, mustard seeds, black peppercorns, and optional red pepper flakes. Heat over medium-high flame, stirring occasionally, until it reaches a rolling boil. Allow to boil for about 2-3 minutes.

Once the brine is ready, carefully pour it over the prepped vegetables in a heat-proof bowl. Gently press the vegetables down to submerge them completely. Allow the mixture to cool to room temperature for about 1 hour.

After the mixture has cooled, pack the pickled vegetables into clean glass jars, layering them to ensure full coverage. Pour over any remaining brine.

Seal the jars tightly with lids, then place them in the refrigerator for at least 24 hours. For best flavor, let sit for 3-5 days.