Add the kiwi, orange juice and optional maple syrup to a blender and blend until completely smooth.
Pour into a small saucepan and whisk in the agar agar powder.
Bring to a boil while whisking continuously, then reduce to a gentle simmer for 2 minutes to activate the agar agar.
Don’t worry if the mixture doesn’t thicken much while heating. Agar agar sets as it cools, not while it’s simmering.
Allow the mixture to cool for 2 to 3 minutes.
Pour into silicone moulds - this makes 12 x 25ml jellies.
Immediately top with the optional strawberry hearts, gently pressing them onto the surface so they stay in place.
Cover loosely and refrigerate for 1 to 2 hours, or until firm.