When using a fruit purée to make gelatin, begin by softening the gelatin in a little bit of water. (If you are using a thin puree like watermelon, you can soften the gelatin in a little bit of the cold purée instead.) Use around 3 tablespoons of water for every tablespoon of gelatin.
Make the fruit purée by placing the small fruits, or small pieces of larger fruits, into a blender container and blending until smooth. Fruits with lots of water like watermelon will make a thin, juice-like puree that is perfect for making a smooth gelatin. Other fruits, like berries, will make a thicker puree that you can water down (with some water, coconut water, or juice) for a smoother gelatin. You can also strain out the small seeds of fruits like berries. Purée enough fruit to end up with around 2 cups of puree mixture (including added liquid, if used).
Pour around 1 cup of the fruit purée into a saucepan. Cook it on low to medium heat.
Add the softened gelatin to the saucepan with the fruit puree and stir, over the heat, until the gelatin has dissolved.
Remove the saucepan from the heat, and pour in the rest of the fruit puree, stirring it until the cool purée is well incorporated into the warm gelatin mixture.
Taste the mixture for sweetness. Add some honey or maple syrup (or another sweetener)if you feel the mixture needs sweetening.
Pour the mixture into serving dishes and refrigerate until the gelatin is fully set.
Making gelatin from juice
Soften the gelatin in around ¼ cup of the juice.
Heat around ¾ cup of the juice over low to medium heat in a saucepan.
Add the softened gelatin to the saucepan with the juice, and mix together well until the gelatin is completely dissolved.
Remove from the heat source and add in the remaining juice, stirring until well incorporated. You can also add honey or maple syrup to sweeten it more, as needed.
Pour the mixture into serving dishes, and put into the refrigerator until the gelatin sets.
Nutritional information based on using 2 cups of pineapple juice and no added sweetener.When cooking the gelatin mixtures, they don't need to come to a boil but should be warm enough to dissolve the gelatin well.A vegan "gelatin" can be made with agar powder. (Begin with half a tablespoon of agar powder to check the consistency. You can reheat with more if you feel it needs it. (Too much agar makes a rubbery dessert.)If using agar, you will need to boil the mixture to activate it. Once activated, it should gel even at room temperature. If it doesn't gel, cook a bit longer.