In a medium saucepan, combine the chopped rhubarb, granulated sugar, and water. Stir to combine.
Bring the mixture to a boil over medium-high heat, stirring occasionally until the sugar is dissolved.
Reduce the heat to low and simmer gently for 20 to 25 minutes, or until the rhubarb has completely broken down and the mixture has thickened slightly.
Remove the pan from the heat and let the mixture cool for 10 to 15 minutes. Stir in the fresh lemon juice, if using.
Strain the mixture through a fine-mesh sieve into a clean glass jar or container, pressing down gently on the solids with the back of a spoon to extract as much liquid as possible.
Let the finished syrup cool completely before sealing the container and storing it in the refrigerator.
Notes
Zero Waste Tip: Do not throw away the leftover rhubarb pulp! It makes a delicious, tart jam that is perfect spread on toast or stirred into yogurt.
•Fruit Variations: Add 1 cup of fresh strawberries or blueberries to the saucepan along with the rhubarb for a mixed berry syrup.
•Storage: Store in an airtight container in the refrigerator for up to 2 weeks, or freeze in a freezer-safe container for up to 3 months. Shake well before using.