Combine the remaining sugar with the strawberries, water, and lemon juice in a small saucepan. Bring the mixture to a boil. When a full boil is achieved, transfer the mixture to a food mill and purée it.
Combine the strawberry purée with the rhubarb in a small saucepan. Bring to a boil over high heat. Boil for 2 minutes. Transfer the mixture to a bowl and refrigerate for at least an hour.
Divide the rhubarb and some of the strawberry juice among serving plates.