Preheat the oven to 180C, and line a 24cm spring based cake tin with baking paper.
Boil the oranges and lemon for an hour.
Drain and set aside to cool.
Peel half of one boiled orange and add it and the remaining whole fruit to a food processor. Process until smooth.
Sift the coconut flour, almond meal and baking powder in a bowl.
In a smaller bowl beat the egg yolks together with the agave syrup.
Mix the citrus pulp and egg syrup through the flour and almond meal.
Beat the egg whites until stiff then fold them through the cake mix.
Bake the cake for 15 minutes at 180C then reduce the heat to 150 and bake for a further 75 minutes.
Turn out the cake to cool and serve it with vanilla yoghurt or cardamom custard.