Choose a fully ripe cucumber that has turned yellow or orange and is soft
Cut the cucumber open and scoop out the seeds
Place the seeds and pulp in a jar with a little water
Let the mixture ferment at room temperature for 1 to 3 days
Stir once a day and wait for the good seeds to sink
Remove any mold, pulp, and floating seeds
Rinse the seeds thoroughly in clean water
Spread the seeds in a single layer on a paper towel or screen
Dry the seeds in a cool, dry, well-ventilated place
Turn the seeds occasionally until completely dry
Store the dried seeds in a labeled, airtight container
Keep the container in a cool, dark, dry place