Adapted from Trunch and Kipp, who’ve adapted it from The Joy of Pickling.
1. Buy a pickle jar’s worth of tiny cucumbers (it works well to buy a lot cukes and sort them, using the larger ones for garlic-dill pickles and the tiny ones for cornichons). Wash the cucumbers gently. In a bowl, mix the cucumbers with a cup or so of Kosher salt. Let stand 24 hours.
2. Drain, rinse in cold water, and place in your sterile pickle jar. Add some cut up shallots, bay leaves, fresh tarragon, peppercorns, and a couple of small chile peppers, and leaving at least 1 inch headspace. Fill the jar to the brim with vinegar. Cover the jar tightly with a nonreactive cap, preferably one that is all plastic. Store the jar in a cool, dry, dark place. (We put ours in the refrigerator.)
3. The cornichons will be ready to eat in 1 month, and will keep well, unopened, for about 1 year.