This purple sweet potato jam tastes like an Okinawan sweet potato and haupia pie but in a spreadable form. It's super easy and a great way to use up leftover sweet potatoes. Use the purple jam on toast, as a filling for mochi, pop tarts, breads, or other baked goods.
Wash your Okinawan sweet potato and steam in the microwave for 5-6 minutes or until a fork can easily pierce through the flesh.
Peel sweet potato and transfer purple insides to a blender or food processor.
Add sugar, coconut milk, and pinch of salt to the sweet potato. Blend until smooth.
Transfer blended sweet potato mixture to a large saucepan (the larger the pan, the faster your jam will cook down).
Bring to a simmer and cook, continuously stirring, until mixture reaches your desired thickness for jam. Remember that it will continue to thicken as it cools down.
Add butter and mix it into your jam as the butter melts.
Transfer to a container with an airtight seal and store in the fridge.