This made 4 pint jars
2 lbs gherkins
10-12 individual cocktail onions, trimmed and peeled
¼ cup kosher salt
5″ branch tarragon
2 tsp brown mustard seeds
2 tsp yellow mustard seeds
4 cups distilled white vinegar
Cover the cucumbers with the kosher salt and let them sit for 2 hours, then rinse the salt off. Split up the other dry ingredients into jars, boil the vinegar, then fill the jars with it and water bath can them for 10 minutes. Wait 2 weeks.
These turned out great, the flavor seems pretty much perfect in a side-by-side comparison. Maille cornichons have coriander seed too, but I didn't have any. I couldn't tell a difference, but I will add some next time I try this.
I also would like try this with some pickle crisp, since they turned out a little soft. Some of that might be due to not using the traditional cucumber varieties, and/or my cucumbers being slightly larger than is typical for the Maille cornichons.