Begin by dicing approximately 3 cups of fresh or frozen rhubarb into small pieces, about 1 cm thick. Set aside as you gather the other ingredients.

In a medium saucepan, combine the diced rhubarb, honey, still water, and basil. Over medium heat, bring to a boil, then reduce to low and simmer for about 12 minutes until the rhubarb is soft.

Strain the mixture through a fine mesh sieve, using a spoon to press down and extract as much liquid as possible to leave behind solids.

To serve, fill tall glasses with ice cubes, pour in about ½ inch of cooled rhubarb syrup, and top off with sparkling water. Stir gently to combine and enjoy!