In a small saucepan, mix together the lemon juice, water, and cornstarch.
Stir until smooth.
Heat over medium heat until the mixture begins to boil.
Stirring constantly, lower heat and cook until mixture turns from milky to opaque and thickens.
Set aside to cool.
Stir in strawberry-kiwi mix.
Add a few drops of water if the mixture becomes too thick to spread evenly.