In a small saucepan, add the vinegar, water, honey and salt. Cook over medium heat, stirring occasionally, until the mixture comes to a low boil and the salt is dissolved; set aside.
In a 1-litre glass jar with a tight-fitting lid, add the garlic, red pepper flakes, peppercorns, mustard seeds and thyme. Cover the jar and shake until the seasonings are well combined. Add the radishes to the jar. Pour in the hot vinegar mixture. Cover the jar and shake gently. Cool the pickles on the countertop. Cover and refrigerate. For the best flavour, refrigerate the pickles for about 24 hours before serving. They will keep well in the refrigerator for up to one month.