These drinks are great served at a cocktail party or garden party, passed around on a platter with small demitasse spoons. They’re bright yellow and taste of citrus with the unmistakable anise-y twang of Herbsaint, a New Orleans creation that debuted right after the repeal of Prohibition. Crafted to take the place of outlawed absinthe and imported Pastis, Herbsaint is an essential ingredient in the Sazerac cocktail and oysters Rockefeller.–David Guas
Pour 1/2 cup of cold water into a small bowl, sprinkle with the gelatin, and set aside.
Bring the remaining 1/2 cup of cold water and the sugar to a boil in a small saucepan. Immediately turn off the heat.
Stir the club soda, lemon juice, and Herbsaint together in a large bowl. Stir the gelatin mixture into the warm sugar water and whisk until dissolved. Pour the gelatin mixture into the bowl with the club soda and stir to combine. Pour the mixture into an 8-inch-square baking dish or small shot glasses, cover with plastic wrap, and refrigerate until set, about 3 hours or overnight. (You can keep the lemon-Herbsaint poppers in the refrigerator in an airtight plastic container or in the baking dish covered with plastic wrap for up to 1 week.)
If using a baking dish, set a glass with hot water on your work surface. Dip a paring knife into the hot water and use it to cut the pan of jelled Herbsaint into 1-inch squares. Place a burner on low heat and hold the baking dish over the burner for a split second to release the cubes from the pan. Invert the pan onto a cutting board or platter; the cubes should pop right out.
If using shot glasses, serve as is with a small spoon.