Use red or pink rhubarb stalks for the brightest color. Add a few strawberries while simmering for a deeper pink drink. For a rhubarb fizz lemonade style, add extra lemon juice. Store leftover rhubarb syrup in the fridge for up to 5 days. Don’t mix the sparkling water into the syrup until serving. For 6 servings, combine 1 cup rhubarb syrup, 1/4 cup fresh lemon juice, 3 to 4 cups chilled sparkling water, and ice. Add sparkling water right before serving so the Rhubarb Fizz stays bubbly.