Cut watermelon. Separate the watermelon from the rind. Leave small amount of red on the rind.
Peel the outer green off.
Cut into bite size pieces.
Wash to disinfect mason jars. Place watermelon rind chunks into jars. Leave a 1/2 inch head space.
Add water, apple cider vinegar with lemon, sugar, peppercorns, red pepper flakes, salt into a pot. Bring to boil. Stir until sugar is dissolved.
Remove from heat. Let cool slightly. Pour mixture into jars over the watermelon rind.
Add lids to jars. Let sit in the refrigerator for a few hours to a few days before eating. Enjoy!