Preheat oven to 170oC. Grease a 6.5cm deep, 11cm x 21cm (base) loaf pan. Line base and sides with baking paper, allowing a 2cm overhang at both long ends.
Combine coconut, sugar and flour in a large bowl. Whisk sour cream, egg and vanilla together in a bowl. Add bananas to egg mixture and stir until well combined. Add banana mixture to coconut mixture. Gently stir to combine.
Spoon mixture into prepared pan. Smooth the surface. Bake for 1 hour or until a skewer inserted into the centre comes out clean. Stand loaf in pan for 15 minutes. Lift onto a wire rack. Allow to cool completely.
To make passionfruit glaze, sift icing sugar into a bowl. Add passionfruit pulp and stir to form a thick paste. Microwave, uncovered, on high for 45 seconds or until warm and runny. Pour glaze over loaf. Serve.