Mix the brine ingredients in a saucepan over med-high heat for about 5 minutes to dissolve sugar and salt. (Remove from direct heat, so it doesn't continue to evaporate.)
Slice the jalapenos into ¼-inch slices and slice the radishes thinly into coins. TIP: Always wear food-safe gloves and avoid touching your face when handling hot peppers.
Divide the peppercorns in the bottom of each jar. Layer the jalapenos and radish with the garlic into the jars.
Pour the hot brine over the contents in the jar to just below the rim (the brine should cover all the vegetables).
Cool to room temperature, secure the lid and refrigerate for up to 2 months.
Video
Notes
TIP: If you use a pickle weight in your jar, leave room for it on top of your stacked radishes and jalapenos. Pickle weights are handy for keeping all ingredients submerged.