Trim ends and dice the rhubarb. Place them in a heat-proof glass jar.

In a medium saucepan over medium heat, bring the sugar, water, zest, and lemon juice to a boil.

Turn off the heat and carefully pour the hot liquid over the rhubarb. Use a spoon if needed to make sure the rhubarb is completely submerged in the liquid. Let this sit on the counter until it’s close to room temperature. Then cover and transfer to the fridge for around a day. The rhubarb will keep in the fridge for 2-3 weeks.