Preheat the oven to 180°C (350°F). Line the bottom of a 13x36 cm (5x14 inch) rectangular tart tin with a removable bottom.
To make the crust: Add all ingredients to a food processor. Process for 1 minute or until the ingredients are combined. The mixture should stick together when pinched between two fingers. If the mixture is still a bit dry, add some extra water and process until the mixture can be pinched between two fingers.
Firmly press the crust mixture along the bottom and sides of the tart tin. Bake for 15 minutes or until the surface is golden brown. Set aside to cool.
To make the filling: Add all ingredients to the food processor. Process until the mixture is combined and very smooth and there should be no chunks of tofu or chocolate. Pour the mixture into the cooled tart case.
Set aside the tart in the fridge for at least 4 hours or until set.
To make the candied kumquats: Add the sweetener and water to a small saucepan over high heat. Bring the sweetener to a boil and add the kumquats. Quickly and gently toss the kumquats so they are all covered in the syrup. Reduce the heat to medium-low and allow the kumquats to cook for 5-10 minutes or until the syrup has reduced.
Spread the warm kumquats in a single layer on a lined baking tray and allow them to cool.
To assemble: When the kumquats have cooled, arrange them on the tart as desired. Serve the tart as desired.
The tart can be stored in an airtight container in the fridge for up to 5 days or in the freezer for up to 1 month.