Prepare your jars by washing them in warm, soapy water or run them through the dishwasher. Submerge them in hot simmering water until ready to use. Always use new snap lids and wash them also in warm, soapy water. Leave them in a bowl of hot water until ready to use.

In a large saucepan add in the vinegar, water, and salt and bring to a boil. Stir to dissolve the salt.

In each jar add in the dill heads, garlic, peppercorns, mustard seed, coriander seed, dill seed and red pepper flakes. Pack in asparagus as tightly as possible. Pour in hot brine and leave 1/2" headspace. Remove any bubbles carefully with a knife. Wipe top and place lid and screw the band on fingertip tight only.

Process in a water bath for 10 min. or as per altitude. Let jars cool on a towel-lined countertop. Make sure all jars have sealed, you will hear them popping while the cool. If any don't seal then refrigerate and eat within a month's time.