6 cups seedless watermelon, cubed (about 2 pounds), plus more for garnish
3 ounces vodka
1 ounce Campari
1 ounce elderflower liqueur
2 sprigs basil, for garnish
Directions
Make the chile oil first so it has time to cool. Combine the oil and chile flakes in a small saucepan over low heat. Warm gently until the oil just begins to shimmer and the flakes darken slightly, about 5 to 7 minutes. Do not let it smoke.
Remove the oil from the heat, stir in the salt, and let it steep for 15 minutes.
Strain the oil through a fine mesh strainer into a small jar and set it aside.
Place the watermelon cubes in a blender and blend until completely smooth.
Set a fine mesh strainer lined with a double layer of cheesecloth over a large bowl. Pour in the blended watermelon.
Let the watermelon drain for 10 minutes, then gather the cheesecloth into a bundle and press firmly to extract as much juice as possible. Discard the solids. You should have about 1 cup of bright, clear juice. Refrigerate until cold, at least 15 minutes.
Combine 4 ounces of watermelon juice, vodka, Campari, and elderflower liqueur in a cocktail shaker and fill it with ice.
Shake hard for 20 seconds.
Double-strain into chilled glasses. Finish each glass with a few drops of chile oil on the surface.
Garnish with basil and cut out watermelon balls or circles on a cocktail pick. Serve immediately.