From the Idun Library

Everything I Want to Eat: Sqirl and the New California Cooking by Jessica Koslow 

Rhubarb Lemonade — Homemade lemonade is always a treat. Plus a simple recipe for a taste of fresh rhubarb and a beautiful color just in time for Valentine's Day. Add a shot of rum or gin if you'd like! Serves 6.

1 1/3 cups (200 g) chopped rhubarb
2/3 cup (135 g) sugar
1/2 cup plus 1 tablespoon (135 ml) fresh lemon juice (about 3 lemons)

Put the rhubarb, sugar, and 1 2/3 cups (400 ml) water in a pot. Bring to a boil, then reduce the heat so that the syrup simmers. Cook for about 20 minutes, stirring every once in a while, until the rhubarb has fallen apart and imbued the liquid with its color. 

While the syrup is still hot, pour it through a fine-mesh sieve into a large measuring cup or bowl. Use a rubber spatula to really press on the rhubarb mush and squeeze out every last drop. Let cool.

There should be about 1 1/4 cups (300 ml) rhubarb syrup. (If there is more, save it for adding later on. My palate loves a good amount of acid, so you may want to use the extra syrup to increase the sweetness to your liking.) Pour the rhubarb syrup into a 1-quart (1-L) jar. Add the lemon juice and 2 cups pluse 1 tablespoon (495 ml) water. Screw on jar's lid and shake well.

Serve chilled over ice.