Place sunflower seeds, nuts, coconut flour, stevia, lime zest and salt into a food processor and pulse into crumbs. Process and slowly add the agave, rice syrup or honey to the mix until the mixture holds together but is still a little bit chunky. Push the dough into the base and sides of the cake tin.
Place all the ingredients for the avocado section of the cake in a blender and blend until smooth, adding more agave, honey or rice syrup and stevia until sweet to your liking. Pour the mix evenly onto the cake crust.
Place all of the ingredients for the yoghurt section into a bowl and mix until combined. It should be a similar consistency to the avocado mixture. Pour evenly over the avocado mixture.
Place in the freezer until just set, around one hour. Slice and serve.