This is how it's done. Cut tomatoes, one variety at a time, and squeeze the pulp, juice, and seeds into a glass or plastic container. You may need to work the cavities with your fingers to liberate all the seeds. Cherry and currant tomatoes can, instead, be pulverized whole in a blender. Fill the container about halfway, but never add water as a substitute for tomato juice; water slows fermentation.

Label and set the containers aside for 96 hours at a temperature not exceeding 70 degrees. (I usually use my kitchen, screened-in porch, potting shed, or garage.) Two or three times daily, stir the fermenting juices to submerge the floating pomace (pulpy material). Mold may form, fruit flies may hover, and one thing is certain -- it will stink to high heaven.

After four days, go to the sink and fill the container with water, stir, and pour off the pulpy water -- but not the seeds, which accumulate at the bottom. Repeat two or three times. Dump the seeds into a fine-mesh sieve, and, under running water, use your fingers to drive any remaining pulp through the strainer and remove the fruit jelly that adheres to the seeds.

Once the seeds are clean, knock the strainer against the sink to remove excess water, and wipe the strainer bottom with an absorbent paper towel.

Quickly flip the strainer over, smacking it on a paper plate, and deposit the seeds. (Practice helps to improve your aim.) Spread the seeds out on the plate, gently pour off drops of water, and label the plate with the variety name and the date. Allow the seeds to dry for three to four weeks in a well-ventilated place at room temperature. Then put them in labeled paper packets. Place these in an airtight container, and store in a dark, dry place. If refrigerated, tomato seeds can last for 20 years.

Text by Amy Goldman; photographs by Victor Schrager

Reproduced with permission of the publisher, Bloomsbury USA, from "The Heirloom Tomato: From Garden to Table -- Recipes, Portraits, and History of the World's Most Beautiful Fruit," published by Amy Goldman. Copyright 2008 by Amy Goldman.