Combine the vinegar, salt, and sugar in a stainless steel or Teflon pan over high heat. Whisk until the salt and sugar are dissolved.
Transfer the liquid into a bowl and whisk in the cold water. Refrigerate brine until it has cooled enough to add to the cucumbers (approx. 30 minutes).
While brine is cooling, place cucumbers into two clean 1-quart jars, leaving a little room to add the dill and spices.
Then, when brine is cooled, add the coriander seeds, garlic cloves, mustard seeds, red pepper flakes, dill sprigs, and chilled brine into jars, dividing evenly.
This is the fun part, as the finished product looks lovely! If necessary, add a bit of cold water until the brine covers the cucumbers.
Cover and refrigerate about 24 hours, then serve. Cucumbers will keep in the refrigerator for up to one month.