Prepare a pint jar for this recipe, or as many as you'd like to make.  (Multiply the recipe for each pint.)

Rinse the cucamelons thoroughly under cold water and remove any stems. Pat them dry with a clean towel.

Add the spices including the mustard seeds, black peppercorns, and red pepper flakes to each jar.

Pack the cucamelons tightly into the jars, leaving about ½ inch of headspace at the top.

In a medium saucepan, combine the apple cider vinegar, sugar, and salt. 

Bring the mixture to a boil, stirring occasionally to dissolve the sugar and salt.

Carefully pour the hot brine over the cucamelons, making sure to cover them completely while maintaining the ½ inch headspace.

Remove air bubbles. Then, wipe the rims of the jars with a clean, damp cloth to ensure a good seal.

Place the sterilized lids on the jars and screw on the bands until fingertip tight.

If canning, position the jars in a boiling water canner, making sure they’re covered by at least one inch of water. Process for 10 minutes (or 15 minutes if you live above 6,000 feet).

Carefully remove the jars from the canner and place them on a towel to cool. 

Check the seals, label, and store.