To make the rhubarb syrup, combine the 2 to 2 1/2 cups fresh rhubarb, 1 cup sugar, and 1 cup water in a medium saucepan. Cook over medium low heat until the rhubarb completely breaks down, 10-15 minutes. Press mixture through a fine mesh sieve trying to extract as much as you can, scraping the bottom of the sieve. Discard remaining solids.
Chill rhubarb syrup in the refrigerator until ready to use.
Process rhubarb syrup, 2 cups strawberries, and 1 cup lemon juice through blender on low speed for 20 seconds. There will be approximately 3.5 to 4 cups of base.
To make lemonade, add 3 cups water or sparkling water to base and serve over ice. Enjoy!