Image by: wintersown
Cut open a ripe and shriveling eggplant and cube it into pieces about thumb size.
Place the cubes in a collander over a pan and sprinkle with some kitchen salt. Toss the cubes to coat evenly with the salt and begin mashing and squeezing them with your hands. This removes much water from the cubes....it will also releases the seeds from the flesh.
Rinse the seeds off the cubes and they'll slip through the collander into the catching pan. Immature seeds will float atop the water. Pour off the floating seeds and any loose bits of eggplant flesh, add more water and stir again to separate the good from the bad. Repeat this step as needed.
Use a small kitchen strainer to sieve the seeds from the water, rinse them well to remove any salt. Spread the seeds in a single layer on a coffee filter for drying. They should dry for at least two or three days, about a week or longer if the weather is damp.